Academic literature on the topic 'Anti-IgA antibody'

IgA antibodies, which are secreted onto the mucosal surface as secretory IgA antibodies (SIgAs), play an important role in preventing influenza virus infection. A recent study reported that anti-hemagglutinin (HA) head-targeting antibodies increase anti-viral functions such as hemagglutination inhibition (HI) and virus neutralization (NT), in addition to HA binding activity (reactivity) via IgA polymerization. However, the functional properties of anti-viral IgA antibodies with mechanisms of action distinct from those of anti-HA head-targeting antibodies remain elusive. Here, we characterized the functional properties of IgG, monomeric IgA, and polymeric IgA anti-HA stalk-binding clones F11 and FI6, and B12 (a low affinity anti-HA stalk clone), as well as Fab-deficient (ΔFab) IgA antibodies. We found that IgA polymerization impacts the functional properties of anti-HA stalk antibodies. Unlike anti-HA head antibodies, the anti-viral functions of anti-HA stalk antibodies were not simply enhanced by IgA polymerization. The data suggest that two modes of binding (Fab paratope-mediated binding to the HA stalk, and IgA Fc glycan-mediated binding to the HA receptor binding site (RBS)) occur during interaction between anti-stalk HA IgA antibodies and HA. In situations where Fab paratope-mediated binding to the HA stalk exceeded IgA Fc glycan-mediated binding to HA RBS, IgA polymerization increased anti-viral functions. By contrast, when IgA Fc glycan-mediated binding to the HA RBS was dominant, anti-viral activity will fall upon IgA polymerization. In summary, the results suggest that coordination between these two independent binding modules determines whether IgA polymerization has a negative or positive effect on the anti-viral functions of anti-HA stalk IgA antibodies.

IgA antibodies, which are secreted onto the mucosal surface as secretory IgA antibodies (SIgAs), play an important role in preventing influenza virus infection. A recent study reported that anti-hemagglutinin (HA) head-targeting antibodies increase anti-viral functions such as hemagglutination inhibition (HI) and virus neutralization (NT), in addition to HA binding activity (reactivity) via IgA polymerization. However, the functional properties of anti-viral IgA antibodies with mechanisms of action distinct from those of anti-HA head-targeting antibodies remain elusive. Here, we characterized the functional properties of IgG, monomeric IgA, and polymeric IgA anti-HA stalk-binding clones F11 and FI6, and B12 (a low affinity anti-HA stalk clone), as well as Fab-deficient (ΔFab) IgA antibodies. We found that IgA polymerization impacts the functional properties of anti-HA stalk antibodies. Unlike anti-HA head antibodies, the anti-viral functions of anti-HA stalk antibodies were not simply enhanced by IgA polymerization. The data suggest that two modes of binding (Fab paratope-mediated binding to the HA stalk, and IgA Fc glycan-mediated binding to the HA receptor binding site (RBS)) occur during interaction between anti-stalk HA IgA antibodies and HA. In situations where Fab paratope-mediated binding to the HA stalk exceeded IgA Fc glycan-mediated binding to HA RBS, IgA polymerization increased anti-viral functions. By contrast, when IgA Fc glycan-mediated binding to the HA RBS was dominant, anti-viral activity will fall upon IgA polymerization. In summary, the results suggest that coordination between these two independent binding modules determines whether IgA polymerization has a negative or positive effect on the anti-viral functions of anti-HA stalk IgA antibodies.

Objectives. We aimed to evaluate the value of immunoglobulin (Ig) G, IgM, and IgA isotypes of anti-double-stranded DNA (anti-dsDNA) and anti-C1q antibody in diagnosing systemic lupus erythematosus (SLE) patients and elucidate their association with disease activity and lupus nephritis. Methods. Blood samples were obtained from 96 SLE patients, 62 other autoimmune disease patients, and 60 healthy blood donors. Anti-dsDNA IgG, IgM, and IgA isotypes and anti-C1q antibody were measured by enzyme-linked immunosorbent assay. Disease activity of SLE patients was assessed according to the SLE Disease Activity Index score. Results. When specificity was greater than 90%, the sensitivity of anti-dsDNA IgG, IgM, and IgA isotypes and anti-C1q antibody in diagnosing SLE was 75%, 45%, 33%, and 49%, respectively. The prevalence of anti-dsDNA IgG (p=0.002), anti-dsDNA IgA (p=0.028), and anti-C1q antibody (p=0.000) in active cases was significantly higher than those in inactive ones. In addition, the presence of anti-C1q antibody was associated with renal involvement (p=0.032). Anti-dsDNA IgM showed no significant association with disease activity, but it was inversely linked with lupus nephritis (p=0.005). When anti-dsDNA IgG and IgA and anti-C1q were combined to evaluate SLE disease activity, the specificity reached the highest level (90%). When anti-C1q positive was accompanied by anti-dsDNA IgM negative, the specificity of diagnosing lupus nephritis was up to 96%. Conclusions. This study demonstrated the role of anti-dsDNA IgG, IgM, and IgA isotypes and anti-C1q antibody alone or combination in diagnosing SLE. Anti-dsDNA IgG and IgA and anti-C1q were shown to be associated with disease activity, while anti-dsDNA IgM and anti-C1q were associated with lupus nephritis. When the related antibodies were combined, the diagnostic specificity was significantly higher.

Background: Henoch Schönlein purpura also known as IgA vasculitis is described histologically by IgA deposition in the blood vessel walls and presents with kidney involvement, palpable purpura, arthralgia, and abdominal pain. Our study aims to evaluate the association between anti-phospholipid antibody, anti-cardiolipin antibody, anti-beta(2) glycoprotein 1 antibody and Anti-phosphatidylserine/prothrombin antibodies and IgA vasculitis. Treatment response with intravenous steroids and cyclophosphamide was also studied based on resolution of antibody titer.Methods: We conducted an observational study in three Rheumatology clinics at Ahmedabad, India. Data was collected for a period of 6 months. Diagnosis of IgA vasculitis was determined based on the International Chapel hill consensus conference 2012. Disease activity was assessed based on antibody titer, histological grading and through a pre-determined clinical form to assess objective clinical symptoms. P value of less than 0.05 was considered significantResults: Study evaluated antibody titer of 178 patients. Sixty one percent of the patient's had positive anti-phospholipid antibody titer with predominant antibody subtype as IgG. Inflammatory markers were significantly higher in patient having anti-phospholipid antibody titer. Anti-phospholipid antibody was present in 100 percent patients who had vascular thrombosis. IgG subtype of anti-cardiolipin antibody were found in 60 percent of the patients with renal complication.Conclusions: Anti-phospholipid antibody have a close association with IgA vasculitis. Anti-phospholipid antibody has a significant role in mounting inflammatory response and vascular thrombosis. Combination treatment of intravenous steroids and cyclophosphamide found to be more effective in resolution of titer

ABSTRACT We monitored 93 subjects cured of amebic liver abscess (ALA) and 963 close associate controls in Durban, South Africa, and determined by enzyme-linked immunosorbent assay that the intestinal immunoglobulin A (IgA) antibody response to the Entamoeba histolytica galactose-inhibitable adherence lectin is most accurately represented by a complex pattern of transitory peaks. One or more intestinal anti-lectin IgA antibody peaks occurred in 85.9% of ALA subjects over 36 months compared to 41.6% of controls (P < 0.0001). ALA subjects exhibited a greater number of anti-lectin IgA antibody peaks (P < 0.0001) than controls. In addition, their peak optical density values were higher (peak numbers 1 to 3, P < 0.003), peaks were of longer duration (for peaks 1 and 2, P ≤ 0.0054), and there was a shorter time interval between peaks (between 1 and 2 or 2 and 3, P ≤ 0.0106) than observed for control subjects. A prior E. histolytica infection was associated with the occurrence of an anti-lectin IgA antibody peak (79.1%, P < 0.0001) more so than for Entamoeba dispar infection (57.2%, P < 0.001). The annual number of anti-lectin IgA antibody peaks in ALA subjects was 0.71 per year, compared to just 0.22 in controls (P<0.0001), indicating a higher rate of exposure to the parasite than previously appreciated. Anti-lectin IgA antibody peaks were of higher amplitude following a E. histolytica infection compared to E. dispar (P = 0.01) and, for either, were of greater height in ALA subjects than controls (P < 0.01). ALA subjects demonstrated greater clearance of amebic infection after an anti-lectin IgA antibody peak compared to controls, and only 14.3% remained with a positive culture after the peak, compared to 38.9% in controls (P = 0.035). In summary, this prospective controlled longitudinal study elucidated the dynamic nature of the human intestinal IgA antibody response to E. histolytica and E. dispar infection and revealed that ALA subjects exhibit heightened intestinal anti-lectin IgA antibody peaks that are associated with clearance of E. histolytica and E. dispar infection.

ABSTRACTSince the 23-valent pneumococcal polysaccharide vaccine (PPV23) is less effective for older adults than for young adults, it is important to investigate the immunologic basis for the reduced efficacy of PPV23 among older adults. We determined the effectiveness of PPV23 among young (n= 55) and older (n= 44) adults by measuring the serum IgG, IgM, and IgA concentrations and opsonic capacities against serotypes 14, 18C, and 23F. While young and older adults showed no difference in levels of IgG antibodies against pneumococcal polysaccharide (PPS), older adults had lower IgA and IgM antibody levels than young adults for all three serotypes. In both age groups, anti-PPS IgA or IgM antibody levels were much lower than anti-PPS IgG antibody levels. Young adults showed higher opsonic capacities than older adults for serotypes 14 and 23F. In order to determine the effects of anti-PPS IgA or IgM antibodies on the functional difference between young and older adults, anti-PPS IgA or IgM antibodies were removed from immune sera by affinity chromatography. The difference in opsonic capacity between young and older adults disappeared for serotypes 14 and 23F (but not for serotype 18C) when IgM antibody was removed. However, there was no significant difference between the two age groups when IgA antibody was removed. In conclusion, even though anti-PPS IgG antibody levels are high compared with anti-PPS IgM antibody levels, the low levels of anti-PPS IgM antibody alone can explain the functional difference observed between young and older adults immunized with PPV23 with regard to some pneumococcal serotypes.

SUMMARYEnzyme-linked immunoabsorbent assay (ELISA) was used to titrate virus-specific IgG, IgM and IgA levels in nasal secretions, lung lavage fluids and serum samples sequentially obtained from lambs experimentally infected with bovine respiratory syncytial virus (RSV). Virus-specific IgG and IgM responses were measured by the indirect double antibody sandwich ELISA using anti-bovine RSV monoclonal antibody, as capture antibody, and peroxidase-conjugated anti-sheep IgG and anti-sheep IgM. Virus-specific IgA antibodies were measured by antibody capture assay using anti-sheep IgA (α–chain specific) and anti-bovine RSV monoclonal antibodies.Bovine RSV-specific IgM and IgA antibodies were detected in the serum samples within 6 days post-inoculation (p.i.). Virus-specific IgC antibodies appeared in serum samples 4 days later. In nasal secretions, IgA antibodies appeared 7 days p.i. but IgM antibodies were not detected until 12–16 days p.i. In serum samples, IgM titres were predominant for the first 2 weeks p.i. IgC titres becoming predominant thereafter. In nasal secretions and lung lavage fluids, IgA titres were significantly higher than IgM or IgG titres up to 21 days p.i. (0·01).

Anti-IgA Antikörper werden häufig als Ursache nicht-hämolytischer Transfusionsreaktionen angesehen. Die Inzidenz solcher Reaktionen schwankt zwischen 1:17.000 bis 1:770.000 und beruht größtenteils auf Fallberichten. Die Bedeutung dieser Antikörper, obwohl mit einer Prävalenz von 1: 18 bis 1:1.250 relativ häufig vorkommend, konnte in den circa vierzig Jahren seit ihrer Entdeckung nicht eindeutig geklärt werden; verschiedene Spezifitäten der Antikörper mit unterschiedlichen Reaktionen erschweren die Diagnose und eine klare Schematisierung. Ein Nachteil war bisher das Fehlen einer schnellen und unkomplizierten Nachweismethode, die in vielen Laboratorien angewandt werden kann. Die Ende der sechziger Jahre entwickelte Die Ende der 1960’er Jahre entwickelte Passive Hämagglutination (PHA) ist oft ungenau und unterliegt starken Schwankungen, kann aber relativ einfach durchgeführt werden und ist deshalb die Hauptmethode in der Diagnose von anti-IgA gewesen. Neuere und genauere Methoden wie Radio Immuno Assay (RIA) und Enzyme Linked Immunosorbent Assay (ELISA) sind weder schnell durchzuführen noch in vielen Laboratorien verfügbar. In dieser Arbeit wird eine neue Agglutinationsmethode, Particle Gel Immuno Assay (PaGIA) evaluiert und mit der PHA verglichen. Im ersten Teil wurden die Seren 105 gesunder Spender untersucht: 70 führten zu Reaktionen im PHA mit Titern bis 1:80 während keines im PaGIA reagierte, was die Spezifität des PaGIA unterlegt. Anschließend wurden elf Seren von Patienten mit selektivem IgA Mangel (sDIgA) und 23 Seren von Patienten mit variablem Immundefektsyndrom (CVID) auf das Vorliegen eines anti-IgA Antikörpers untersucht. Fünf Seren beider Patientengruppen führten in beiden Tests zu Agglutinationen und ein Serum (sDIgA) reagierte mit einem Titer von 1:1 in der PHA aber nicht im PaGIA. Die hier gefundenen Prävalenz (22% sDIgA, 45% CVID) und Größe der Titer (sDIgA>CVID) von anti-IgA stimmt mit den bisherigen Erkenntnissen überein. Weitere Untersuchungen konnten die Stabilität des PaGIA bzw. dessen Beads und Reproduzierbarkeit der Ergebnisse über mehrere Monate als auch die Möglichkeit subklassenspezifisches anti-IgA nachzuweisen darlegen. Der PaGIA stellt einen schnell und einfach durchzuführenden Test dar, mit dem anti-IgA Antikörper verschiedener Spezifität verläßlich bestimmt werden können, um Untersuchungen im großen Rahmen durchzuführen, die die Bedeutung der anti-IgA Antikörpern erhellen.
Anti-IgA antibodies are thought to be responsible for non-hemolytic transfusion reactions in one in 17,000 to one in 770,000 number of cases. This incidence is mainly supported by case reports. Despite their relative frequency of one in 18 to one in 1,250, since their discovery approximately forty years ago, the true significance of these antibodies has not yet been determined. Several specificities of these antibodies resulting in different reaction patterns make diagnosis and categorization difficult. Until recently, the lack of a fast and reliable laboratory test was a drawback. This test needed to be easily performed, fast, accurate, reproducible and accessible to many practitioners in many laboratories. The Passive Hemagglutination Assay (PHA), developed in the late 1960’s, is neither precise nor reliable but easy to perform and therefore has been the mainstay in diagnosis of anti-IgA. While newer methods, such as Radio Immuno Assay (RIA) and Enzyme Linked Immunosorbent Assay (ELISA), are neither fast nor easily performed but very precise. This thesis studies and evaluates a new agglutination assay, the Particle Gel Immuno Assay (PaGIA), and compares it to the PHA. In the first part of our study we established the specificity of PaGIA. Sera of 105 healthy blood donors were tested: 70 led to positive reactions with the PHA with titers up to 1:80 while none reacted with the PaGIA. Subsequently, eleven sera of patients with selective deficiency of IgA (sDIgA) and 23 sera of those with Common Variable Immunodeficiency (CVID) were tested for the presence of anti-IgA antibodies. Five sera in each group led to agglutinations in both assays and one serum reacted with a titer of 1:1 in the PHA but not in the PaGIA. The prevalence (22% sDIgA, 45% CVID) and strength of the titers (sDIgA>CVID) of anti-IgA corresponds with current knowledge. Further tests demonstrated the PaGIA’s and its beads stability and reproducibility over several months as well as the possibility for detection of subclass-specific anti-IgA. The PaGIA is a fast and easily performed assay which reliably detects anti-IgA antibodies of different specificities, thereby providing a tool for large scale studies to shed more light on the significance of anti-IgA antibodies.

A transferência passiva de anticorpos da mãe para o filho auxilia na adaptação ao meio externo. No recém-nascido (RN), a colonização pelo Staphylococcus aureus (S. aureus) é precoce, sendo este um importante agente etiológico em infecções neonatais e no lactente jovem, para o qual ainda não se dispõem de vacina. OBJETIVOS: Avaliar as concentrações, títulos e avidez de anticorpos maternos anti-S. aureus do tipo IgG e IgA e a passagem desses anticorpos para os RN por transferência placentária e pelo colostro. MÉTODOS: Estudo caso-controle de 147 parturientes saudáveis. Foram coletadas amostras de soros maternos, de cordão umbilical e colostro. O grupo caso foi definido pela colonização nasal natural pelo S. aureus, sendo que para cada caso (n=49) foram selecionados 2 controles (n=98). Foram utilizadas as metodologias de imunoturbidimetria para dosagem de IgG total, ensaio imunoenzimático para dosagem IgA total e para a aferição das concentrações e títulos de anticorpos específicos anti-S. aureus (IgG sérica, subclasses séricas IgG1 e IgG2, IgA de colostro e os índices de avidez). Foram aplicados testes não paramétricos de Wilcoxon para amostras pareadas e de Mann-Whitney para amostras não pareadas, com intervalo de confiança de 95%, nível de significância p < 0,05. RESULTADOS: No grupo caso, as concentrações séricas de IgG total materna foram maiores mas com menor taxa de transferência placentária de IgG total, ocorrendo o inverso para o grupo controle. Não foram observadas diferenças nas concentrações séricas de IgG materna anti-S. aureus entre os grupos, mas com taxa de transferência placentária significantemente menor no grupo caso. Observou-se que os títulos específicos de IgG1 anti-S. aureus foram mais baixos no soro materno e no cordão do grupo caso, com taxas de transferência similar para os grupos caso e controle. Para os títulos específicos de IgG2 anti-S. aureus, não foram observadas diferenças entre os grupos caso e controle, com taxas de transferência similares entre os grupos. Observou-se que os títulos de IgG2 foram maiores que os de IgG1, tanto no soro materno como no de cordão em ambos os grupos. No soro materno e de cordão, não foram encontradas diferenças entre os grupos nos ensaios de avidez de IgG anti-S. aureus. No estudo de colostro, a concentração de IgA total foi maior no grupo caso, mas sem diferenças entre os grupos para a IgA anti-S. aureus. A comparação da avidez de anticorpos IgA anti-S. aureus do colostro com a de IgG anti-S. aureus do soro materno, em ambos os grupos, mostrou que a avidez de IgA foi maior. CONCLUSÕES: Os resultados demonstraram que a colonização nasal materna por S. aureus não esteve associada com uma maior transferência para o RN de anticorpos IgG ou IgA específicos via placenta ou colostro. A maior transmissão de títulos elevados de IgG2 específicos para o recém-nascido, isto é, anticorpos com uma baixa atividade opsonizante, reitera a maior susceptibilidade neonatal para este agente patogênico. A IgA secretora no colostro apresentou melhor índice de avidez do que a IgG do soro, o que corrobora com a importância da amamentação nos primeiros meses de vida
The passive transfer of antibodies from mother to child assists in adjustment to the external environment. In the newborn (NB), colonization by Staphylococcus aureus (S. aureus) occurs early, which is an important etiologic agent in neonatal and young infant infections, for which no vaccine is available. AIMS: To evaluate concentrations, titers and avidity of anti-S. aureus maternal IgG and IgA antibodies and transmission of these antibodies to the newborns via placental transfer and colostrum. METHODS: Case-control study of 147 healthy pregnant women. Samples of maternal serum, cord blood and colostrum were collected. The case group was defined by natural nasal colonization with S. aureus, and for each case (n = 49) were selected 2 controls (n = 98). Immunoturbidimetric assay was used to measure total IgG, and immunoenzymatic assay to measure total IgA in colostrum and anti-S. aureus concentrations and titers (serum IgG, serum IgG1 and IgG2, colostrum IgA and IgG and IgA avidity indexes). Nonparametric Wilcoxon test for paired samples and the Mann-Whitney test for unpaired samples were applied, with a confidence interval of 95%, significance level of p < 0.05. RESULTS: In the study group, maternal total IgG serum concentrations were higher but with lower total IgG placental transfer ratio, while the opposite occurred for the control group. No differences were observed in anti-staphylococcal maternal IgG serum concentrations between groups, but placental transfer ratio was significantly lower in the case group. It was observed that anti-S. aureus IgG1 titers were lower in maternal and cord serum from the case group, with with similar transfer ratios for case and control groups. Regarding antistaphylococcal IgG2 titers, no differences were observed between case and control groups, with similar transfer ratios between groups. It was observed that specific IgG2 titers were higher than those of IgG1 in both maternal and cord serum from both groups. In maternal and cord blood serum, no differences between groups were found in avidity assays of anti-S. aureus IgG. In colostrum, total IgA concentrations were higher in the case group, but no differences between groups for anti-S. aureus IgA were detected. The comparison of anti-staphylococcal IgA antibodies avidity in colostrum with anti-S. aureus IgG in maternal serum from both groups, showed that IgA presents higher avidity indexes. CONCLUSIONS: The results demonstrated that maternal nasal colonization by S. aureus was not associated with a higher transfer to the NB of specific IgG or IgA antibodies via the placenta or colostrum. The greatest transmission of Sa-specific IgG2 titers to the newborn, i.e., antibodies with low opsonizing activity, reiterates the higher neonatal susceptibility to this pathogen. Secretory IgA in colostrum showed better avidity index than serum IgG, which reinforces the importance of breastfeeding in the early months of life

A Doença Celíaca (DC) é uma doença autoimune que afeta o intestino delgado de indivíduos geneticamente susceptíveis após contato com o glúten. Diversos estudos têm relatado aumento da prevalência ao longo dos anos. Objetivo: Determinar a prevalência de DC em pacientes adultos sem diarreia encaminhados à Disciplina de Gastroenterologia do HUPE da UERJ para serem submetidos a Endoscopia Digestiva Alta (EDA).Comparar os resultados do histopatológico das biópsias duodenais com os resultados sorológicos, utilizando o anticorpo antitransglutaminase tecidual IgA (ATGt IgA). Métodos: Pacientes que foram encaminhados ao nosso serviço para serem submetidos a EDA entre Julho de 2008 e Julho de 2010, com idade entre 18 e 85 anos foram aceitos no estudo. Critérios de exclusão foram cirrose, neoplasias do trato gastrointestinal, HIV, uso de imunossupressores e anticoagulantes, diarreia, hemorragia digestiva e DC. Coleta de sangue para pesquisa do anticorpo ATGt IgA (utilizando KIT ORGENTEC - Alemanha), avaliação endoscópica e exame histopatológico das biópsias de segunda porção duodenal foram feitos para cada paciente. Biópsias foram avaliadas de acordo com o critério de Marsh modificado. Resultados: Trezentos e noventa e nove pacientes consecutivos (112 homens, 287 mulheres), média de idade 49,616,4 anos, variando de 18-85 anos, sem diarreia, foram prospectivamente aceitos. Os sintomas clínicos mais prevalentes foram dor abdominal em 99,5%, pirose em 41,1%, plenitude pós prandial em 30,6%, náuseas e vômitos em 21,3%. Os achados endoscópicos foram: normais em 41,6%, lesões pépticas (esofagite, gastrite, duodenite e úlceras) em 41,6%, hérnia hiatal em 5,5%, pólipos gástricos em 3%, neoplasias em 1,3% e miscelânea em 7%. DC foi endoscopicamente diagnosticada em 13 pacientes (3,3%) com mucosa duodenal exibindo serrilhamento das pregas em 8 (2%), diminuição do pregueado em 2 (0,5%) e mucosa exibindo padrão nodular e mosaico em 3 (0,75%). Os achados histopatológicos de duodeno foram normais em 96,7%, duodenites inespecíficas em 2,7% e 3 pacientes (0,75%) confirmaram DC pelos critérios de Marsh modificado (IIIa, IIIb e IIIc). O anticorpo ATGt IgA foi positivo (>10 U/ml) em 1,3% (5/399). Conclusão: Este estudo mostrou que a prevalência de DC em pacientes dispépticos sem diarreia atendidos na Disciplina de Gastroenterologia e Endoscopia do HUPE/UERJ foi de 0,75% (1:133). A acurácia diagnóstica do anticorpo ATGt IgA é boa para pacientes com Marsh III e achados endoscópicos sugestivos. Nenhum dos pacientes tinha alterações Marsh I ou II. A EDA se mostrou um excelente método de triagem para definir os pacientes com graus mais acentuados de atrofia e que se beneficiariam de biópsia e sorologia para confirmação diagnóstica. Os resultados obtidos neste trabalho não justificam uma triagem rotineira de DC.
Celiac Disease (CD) is an autoimmune disease that affects the small intestine in genetically susceptible individuals after contact with gluten. Several studies have reported increased prevalence over the years. Objective:To determine the prevalence of CD in adult dyspeptic patients without diarrhea referred to the Gastroenterology Division at Pedro Ernesto University Hospital in Rio de Janeiro (HUPE- UERJ) to undergo esophago-gastro-duodenoscopy (EGD). Compare the results of histopathology of duodenal biopsies with the serological results using IgA anti-tissue transglutaminase antibody (IgA anti-tTG). Methods: Patients with dyspepsia referred to our clinic to undergo EGD between July 2008 and July 2010, aged 18 and 85 years were enrolled into the study. Exclusion criteria were cirrhosis, gastrointestinal neoplasms, HIV, use of immunosuppressive drugs and anticoagulants, diarrhea, gastrointestinal bleeding and CD. Samples for IgA anti-tTG antibody (using ORGENTEC KIT -Germany), endoscopic evaluation and histological examination of biopsies of the second duodenal portion were made for each patient. Biopsies were evaluated according to the modified Marsh criteria. Results: Three hundred and ninety-nine consecutive patients (112 men, 287 women), mean age 49.6 16.4 years, ranging from 18-85 years, without diarrhea, were prospectively accepted. The most prevalent clinical symptoms were abdominal pain in 99.5%, heartburn in 41.1%, postprandial fullness in 30.6%, nausea and vomiting in 21.3%. Endoscopic findings were normal in 41.6%, peptic lesions (esophagitis, gastritis, duodenitis and ulcers) in 41.6%, hiatal hernia in 5.5%, gastric polyps in 3%, cancer by 1.3% and miscellaneous 7%. CD was diagnosed endoscopically in 13 patients (3.3%) with duodenal mucosa exhibiting scalloped folds in 8 (2%), decreased in the number of folds in 2 (0.5%), nodular mucosa and mosaic pattern in 3 (0.75%).The histopathological findings of duodenum were normal in 96.7%, nonspecific duodenitis in 2.7% and 3 patients (0.75%) confirmed by the CD modified Marsh criteria (IIIa, IIIb and IIIc). IgA anti-tTG antibody was positive (>10U/ml) in 1.3% (5/399). Conclusion: This study showed that the prevalence of CD in patients without diarrhea seen at the Division of Gastroenterology and Endoscopy, Pedro Ernesto University Hospital was 0.75% (1:133). The diagnostic accuracy of IgA anti-tTG is good for patients with Marsh III and suggestive endoscopic findings. None of the patients had Marsh I or II changes. The EGD has proved an excellent screening method to define patients with more marked degrees of atrophy and could benefit from biopsy and serology for diagnosis confirmation. The results of this study do not justify routine screening of CD.

Le SIDA est une infection transmise essentiellement au niveau des muqueuses génitales. Pour empêcher la transmission du virus de l'immunodéficience humaine (VIH-1), il faudrait dresser des barrières efficaces susceptibles de bloquer l'infection dès l'entrée du VIH-1 dans les muqueuses, avant l'établissement de réservoirs muqueux. Les IgA sont les principaux effecteurs immunitaires protecteurs des muqueuses génitales et participent à la protection contre la transmission muqueuse du virus. En effet, chez des femmes hautement exposées au VIH-1 qui restent séronégatives malgré des rapports sexuels non protégés avec des partenaires infectés par le VIH-1 (ESN), les IgA muqueux spécifiques de l'enveloppe virale gp41 avec des activités antivirales cross-clade puissantes sont un corrélat de protection majeur. Mais les muqueuses génitales sont aussi protégées par des IgG dont l'origine et le rôle sont actuellement réévalués. Dans ce travail, nous avons analysé l'influence de l'isotype, A ou G, sur la spécificité épitopique, les fonctions antivirales des anticorps protecteurs de sujets ESN et évalué de nouvelles fonctions antivirales médiées par le fragment constant des IgA. Pour ces études, nous avons d'abord utilisé 2 Fab IgA protecteurs issus d'une banque d'IgA muqueux provenant de femmes ESN spécifiques de régions conservées de gp41 de l'enveloppe du VIH, caractérisés au laboratoire. Ces Fab IgA (FabA) ont d'abord été transformés en Fab IgG (FabG) correspondants par génie génétique puis comparés au niveau immunochimique et fonctionnel. Ces couples FabA/G portent les mêmes paratopes mais diffèrent par leur partie CH1 (alpha ou gamma) qui dicte l'isotype. Nous avons montré que l'isotype et notamment le domaine CH1 de l'anticorps influence : i) l'affinité des Fabs pour leurs antigènes de clades A, B et C par la résonance plasmonique de surface et ELISA : les FabA ont une affinité >50x supérieure aux FabG correspondants ; ii) les fonctions antivirales : les FabA neutralisent plus efficacement l'infection de LTCD4 et le transfert du virus de cellules de Langerhans aux LTCD4 que les FabG correspondants. Puis, en prenant comme modèle expérimental l'anticorps 2F5 sous forme IgA, nous avons caractérisé une nouvelle propriété antivirale pour les IgA médiée par leur domaine Fc et montré que cet isotype est aussi capable d'induire la lyse de cellules infectées par le VIH-1 par Antibody dependent cell cytotoxicity, ADCC. Cette ADCC est médiée par des cellules effectrices (monocytes) de façon FcR alpha-dépendante. De plus, IgA et IgG spécifiques de gp41 agissent en synergie pour augmenter l'ADCC des cellules infectées par le VIH. L'ensemble de ces résultats montre que l'isotype (le domaine CH1) a une influence sur la reconnaissance et l'affinité pour l'antigène, mais aussi sur la qualité de la réponse immunitaire secondaire (fonctions antivirales). Finalement nous avons caractérisé les épitopes conformationnels de ces FabA/FabG sur des gp41 des différentes clades, A, B et C, chacune sous conformation pré et post fusion en utilisant une stratégie de biopanning couplée à une analyse in silico. Nous avons ainsi défini les épitopes conformationnels cross-clade de ces anticorps protecteurs de sujets ESN. Ils pourront servir d'immunogènes dans une stratégie vaccinale visant à reproduire la réponse IgA protectrice des ESN. Au cours de cette étude, nous avons mis en œuvre une stratégie de Reverse Vaccinology 2.0 pour caractériser, à partir d'anticorps de sujets ESN protégés de l'infection par le VIH, des épitopes conformationnels spécifiques de gp41 qui pourraient servir d'immunogènes dans une stratégie vaccinale contre le VIH. Cette approche vaccinale muqueuse pourrait conduire à diminuer les cas de nouvelles infections sexuelles par le VIH chez les femmes (les plus touchées par l'infection au niveau mondiale) mais aussi chez les hommes, ce qui reste un énorme challenge de santé publique
AIDS is an infection transmitted mainly in the genital mucosa. It is at this level that an effective barrier should be developed to block infection from the initial entry of HIV-1 in the genitals, before establishment of mucosal reservoirs. IgA is the main protective antibody at the genital mucosa and has been suggested to be protective in vivo against HIV-1. Hence, mucosal gp41-specific IgA with strong cross-clade antiviral activity are a major protective correlate in Highly HIV- Exposed individuals that remain SeroNegative (ESN) despite unprotected sexual intercourse with infected partners. However, genital mucosa are also protected by IgG whose origin and role are currently reevaluated. In this work, we have analyzed the influence of the antibody isotype, IgA or IgG, on the epitope specificity, antiviral functions of HIV-1 protective antibodies and evaluated new antiviral functions mediated by the constant IgA regions. For this purpose we have used a library of protective Fab IgA derived from ESN women that are specific for conserved regions of the HIV-1 envelope gp41 subunit, already characterized in the laboratory (Tudor et al., Mucosal Immunol, 2009). By genetic engineering, we have first transformed two of these Fab IgA (FabA) into their corresponding Fab IgG (FabG), having the same paratopes but differing from each other by their CH1 domain (alpha or gamma). These two FabA/FabG couples were then analyzed comparatively for their epitope specificity and functional activities. We have shown that the isotype and particularly the CH1 domain influences (i) the affinity of Fabs for their antigens (gp41 and P1 of clades A, B and C) using surface plasmon resonance and ELISA : FabA have a 50- to 100-fold higher affinity than corresponding FabG ; (ii) antiviral functions: FabA more effectively neutralize CD4+ T-cells infection and transfer of HIV-1 from Langerhans cells to CD4+ T-cells than their corresponding FabG. In a second step, taking as experimental model the neutralizing HIV-1 antibody 2F5 as IgA, we demonstrated that IgA specific for gp41 were able to lyse HIV-1 infected cells in a process mediated by their Fc alpha domain, namely antibody mediated cell cytoxicity (ADCC), a function usually attributed to IgG. Furthermore, anti-gp41 IgA and IgG work in synergy to increase HIV-1-infected cell lysis. Altogether, the results show the isotype (the CH1 domain) has an influence on the recognition and affinity for the antigen, but also on the quality of the secondary immune response (antiviral functions). Finally, we characterized epitopes specific from the two FabA/FabG couples using biopanning followed by in silico analysis. Cross clade 3-dimensional epitopes were mapped on gp41 from Clade A, B and C, each in pre- or post-fusion conformation. These analyses allowed to define cross clade 3-dimensional epitopes targeted by these protective antibodies derived from ESN subjects. These epitopes could serve as immunogen in a vaccine strategy aiming at recapitulating the protective ESN IgA response. Altogether, we have used the strategy of Reverse Vaccinology 2.0 to characterize novel immunogens based on 3D-epitopes targeted by mucosal antibodies from individuals resisting HIV infection. These results should be taken into account in the design of an effective vaccine against the active clades of HIV-1 in the world (A, B and C). Such mucosal vaccine approach is necessary to decrease the number of new HIV infections among women (the most affected) but also in men, which remains a huge public health challenge

碩士
中山醫學大學
免疫學研究所
98
OBJECTIVE: Celiac disease(CD) is a inflammatory enteropathy induced by gliadin in genetically susceptible individuals. Recent report showed link between CD and other autoimmune disease .The relationship between anti-gliadin antibody and patients with autoimmune disease were estimated in the study. METHODS: The antigen of gliadin were tested in patients with autoimmune disease by enzyme-linked immusorbent assay(ELISA).The sera sample were consisted of 126 patients with Sjogren’s syndrome(SS),and 84 patients with Systemic lupus erythematosus(SLE),42 patients with Rheumatoid arthritis,42 patients with Diabetes mellitus , 42 patients with Ankylosing spondylitis , 42 patients with Hepatitis C virus and35 patients with Anemia. The 27 serum of health group were also obtained. Results: In analysis of anti-gliadin IgA antibody,12(9.52%)of 126 patient serums with SS,21(25%)of 84 patient serums with SLE,1(2.38%) of 42 patient serums with RA,6(14.3%)of42patient serums withDM,3(8.57%)of 35 patient serums with Anemia, 3(7.1%)of42patient serums with AS, 9(21.43%)of42patient serums with HCV, 1(3.7%) of 27 the health group have antibody reacted with gliadin. Conclusions: Our result shows that the patients with SLE were higher anti-gliadin antibody than patients with other autoimmune disease. The relationship between the patient s with CD and other autoimmune disease should be estimated in the future.

Abnormal regulation of complement is intimately associated with C3 glomerulopathy and atypical haemolytic uraemic syndrome. Atypical haemolytic uraemic syndrome is characterized by renal thrombotic microangiopathy due to an inability to regulate complement activation along the renal endothelium. The development of thrombosis is critically dependent on the ability to activate C5. Eculizumab, a monoclonal anti-C5 antibody, is an effective therapy for this condition. C3 glomerulopathy refers to glomerular lesions characterized by accumulation of C3 in the absence of immunoglobulin. The prototypic example is dense deposit disease. This condition is associated with impaired regulation of the alternative pathway in plasma. In other subtypes of C3 glomerulopathy, familial studies have identified mutations within the complement factor H-related protein family. Polymorphic variation within this protein family also influences susceptibility to IgA nephropathy. The mechanism underlying these associations remains unknown and is the subject of ongoing research efforts.

Small vessel vasculitis is vasculitis affecting predominately small intraparenchymal arteries, arterioles, capillaries, and venules. There are two main types: antineutrophil cytoplasmic antibody associated and immune complex mediated. The ANCA associated vasculitides are discussed in chapter 19.3 IgA vasculitis (IgAV) was formerly known as Henoch Schönlein purpura. The revised nomenclature reflects the importance of IgA vasculitis in pathogenesis. The Chapel Hill Consensus Conference defined IgA vasculitis as ‘vasculitis with IgA1-dominant immune deposits, affecting small vessels (predominantly capillaries, venules, or arterioles)’. IgA vasculitis often involves skin and gut, and frequently causes arthritis. Glomerulonephritis indistinguishable from IgA nephropathy may occur. Its aetiology is unknown, but it frequently occurs after an infection several days to weeks before. The most frequently isolated organism is beta-haemolytic streptococcus. Drugs such as a penicillin, ampicillin, erythromycin, and non-steroidal anti-inflammatory drugs have been reported as precipitating agents. There is an association with HLA-DRB1*01 in Caucasians and there appears to be a familial association.

Many rheumatological conditions have systemic effects. Antibody production, complement activation, and protein deposition can all result in damage to the kidney, sometimes with devastating sequelae. Systemic lupus erythematosus—lupus nephritis is clinically evident in up to 75% of patients with systemic lupus erythematosus (SLE), and endstage renal disease is seen in 5 to 10% of patients at 10 years. Proteinuria is the most common clinical presentation, closely followed by nonvisible haematuria and tubular abnormalities. Patients with active lupus nephritis often have features of active SLE. The gold standard for lupus nephritis diagnosis is a renal biopsy, with treatment related to histopathological features observed. Adjunctive immunosuppressive agents such as rituximab and tacrolimus are emerging as increasingly important lupus nephritis therapies. Systemic sclerosis is a multiorgan connective tissue disease. Most renal manifestations are clinically silent. By contrast, the scleroderma renal crisis is characterized by accelerated-phase hypertension and impaired renal function. It carries a high mortality risk. Rheumatoid arthritis can affect the kidneys in many ways, most commonly by causing amyloid A amyloidosis. This presents with proteinuria, often severe enough to cause nephrotic syndrome, with 50% progressing to endstage renal failure after 5 years (90% at 10 years). Renal vasculitis, mesangiocapillary glomerulonephritis, and mesangial IgA proliferative glomerulonephritis are also described. Gold and penicillamine (now rarely used) can cause proteinuria, sometimes with nephrotic syndrome. Renal involvement in Sjögren’s syndrome is generally mild, but up to a quarter of patients develop acute or chronic kidney disease, typically with evidence of tubular dysfunction. Glomerular abnormalities are rare and the most common histological abnormality is tubulointerstitial nephritis. Drug nephrotoxicity—conventional antirheumatics and over-the-counter nonsteroidal anti-inflammatory drugs are used exceptionally widely in the community and are nephrotoxic. Their almost ubiquitous use, especially during intercurrent illnesses, means they are frequent contributors to acute and chronic kidney damage.

The characterization of platelet reactive alloantibodies and autoantibodies is mandatory for the diagnosis of posttransfusion purpura, neonatal alloimmune thrombocytopenia, autoimmune thrombocytopenia and for the selection of platelet donors prior to platelet transfusions in immunized polytransfused patients. The platelet immunofluorescence test is suitable for the detection of platelet reactive antibodies. In many cases, however, mixtures containing different platelet reactive antibodies have to be dissected.In order to analyze these sera, we have developed a novel enzyme immunoassay based upon monoclonal antibody specific immobilization of platelet antigens (MAIPA). In brief, platelets are incubated simultaneously with the (human) serum to be investigated and a monoclonal (mouse) antibody directed against an epitope on the same platelet membrane glycoprotein (GP). Platelets are then washed and solubilized in TRIS buffered saline containing NP40. The lysed platelets are then pipetted into the wells of microtiter plates, coated with goat anti mouse IgG where mouse anti GP-complexes are immobilized. Human platelet reactive antibodies on the same GP are detected using enzyme labelled goat anti human IgG, IgM, or IgA, respectively. Using mab Gi5, mab FMC25, mab w6.32 directed against epitopes on the glycoprotein complex IIb/IIIa, glycoprotein Ib and HLA class I molecule, respectively, and a panel of typed platelet donors, even sera containing different platelet reactive antibodies are readily analyzed. Results of experiments with platelet specific alloantibodies (anti P1A1, anti P1A2 and anti Bak(a)), autoantibodies (against the GP Ilb/IIIa complex and GP Ib) and a drug dependent antibody show that this assay allows to discriminate all these different platelet reactive antibodies.