Simple Measurement of IgA Predicts Immunity and Mortality in Ataxia-Telangiectasia.

Patients with ataxia-telangiectasia (A-T) suffer from progressive cerebellar ataxia, immunodeficiency, respiratory failure, and cancer susceptibility. From a clinical point of view, A-T patients with IgA deficiency show more symptoms and may have a poorer prognosis. In this study, we analyzed mortality and immunity data of 659 A-T patients with regard to IgA deficiency collected from the European Society for Immunodeficiencies (ESID) registry and from 66 patients with classical A-T who attended at the Frankfurt Goethe-University between 2012 and 2018. We studied peripheral B- and T-cell subsets and T-cell repertoire of the Frankfurt cohort and survival rates of all A-T patients in the ESID registry. Patients with A-T have significant alterations in their lymphocyte phenotypes. All subsets (CD3, CD4, CD8, CD19, CD4/CD45RA, and CD8/CD45RA) were significantly diminished compared to standard values. Patients with IgA deficiency (n = 35) had significantly lower lymphocyte counts compared to A-T patients without IgA deficiency (n = 31) due to a further decrease of naïve CD4 T-cells, central memory CD4 cells, and regulatory T-cells. Although both patient groups showed affected TCR-ß repertoires compared to controls, no differences could be detected between patients with and without IgA deficiency. Overall survival of patients with IgA deficiency was significantly diminished. For the first time, our data show that patients with IgA deficiency have significantly lower lymphocyte counts and subsets, which are accompanied with reduced survival, compared to A-T patients without IgA deficiency. IgA, a simple surrogate marker, is indicating the poorest prognosis for classical A-T patients. Both non-interventional clinical trials were registered at clinicaltrials.gov 2012 (Susceptibility to infections in ataxia-telangiectasia; NCT02345135) and 2017 (Susceptibility to Infections, tumor risk and liver disease in patients with ataxia-telangiectasia; NCT03357978).

Innate Mechanisms in Selective IgA Deficiency.

Selective IgA deficiency (SIgAD), characterized by a serum IgA level below 0.07 mg/ml, while displaying normal serum levels of IgM and IgG antibodies, is the most frequently occurring primary immunodeficiency that reveals itself after the first four years after birth. These individuals with SIgAD are for the majority healthy and even when they are identified they are usually not investigated further or followed up. However, recent studies show that newborns and young infants already display clinical manifestations of this condition due to aberrancies in their immune defense. Interestingly, there is a huge heterogeneity in the clinical symptoms of the affected individuals. More than 50% of the affected individuals do not have clinical symptoms, while the individuals that do show clinical symptoms can suffer from mild to severe infections, allergies and autoimmune diseases. However, the reason for this heterogeneity in the manifestation of clinical symptoms of the individuals with SIgAD is unknown. Therefore, this review focusses on the characteristics of innate immune system driving T-cell independent IgA production and providing a mechanism underlying the development of SIgAD. Thereby, we focus on some important genes, including TNFRSF13B (encoding TACI), associated with SIgAD and the involvement of epigenetics, which will cover the methylation degree of TNFRSF13B, and environmental factors, including the gut microbiota, in the development of SIgAD. Currently, no specific treatment for SIgAD exists and novel therapeutic strategies could be developed based on the discussed information.

TNFRSF13B Diversification Fueled by B Cell Responses to Environmental Challenges-A Hypothesis.

B cell differentiation and memory are controlled by the transmembrane activator and CAML interactor (TACI), a receptor encoded by TNFRSF13B. TNFRSF13B mutations are frequently found in common variable immunodeficiency (CVID) and in IgA -deficiency; yet, ~98% of those with mutant TNFRSF13B are healthy. Indeed, TNFRSF13B is among the 5% most polymorphic genes in man. Other mammals evidence polymorphism at comparable loci. We hypothesize that TNFRSF13B diversity might promote rather than detract from well-being by controlling key elements of innate immunity. We shall discuss how extraordinary diversity of TNFRSF13B could have evolved and persisted across diverse species of mammals by controlling innate and adaptive B cell responses in apparently paradoxical ways.

GLILD Revisited: Pulmonary Pathology of Common Variable and Selective IgA Immunodeficiency.

Common variable immunodeficiency (CVID) and selective immunoglobulin A deficiency (IgAD) often cause chronic lung disease, but the pulmonary pathologic features of these systemic diseases are poorly recognized by pathologists. It has been claimed that CVID cases show a characteristic combination of noncaseating granulomas-lymphoid proliferations termed granulomatous-lymphocytic interstitial lung disease (GLILD). We present 34 surgical lung biopsy cases of CVID and 4 of IgAD. Noncaseating granulomas were seen in 23/34 (68%) CVID and 2/4 (50%) IgAD cases. A statistically identical pattern of benign lymphoid proliferation was found in CVID and IgAD whether or not granulomas were present. Organizing pneumonia, sometimes considered a part of GLILD, was seen in 25/34 (74%) CVID and 2/4 (50%) IgAD cases and did not correlate with the presence of granulomas. On follow-up, 3 CVID patients died (only 1 of pulmonary disease), while 21 others are alive at 1 to 300 months with no difference by presence or absence of granulomas. Three IgAD patients with follow-up are alive. We conclude that CVID and IgAD are indistinguishable in surgical lung biopsies and a subset of both show patterns that would qualify as GLILD, while other cases lack granulomas but have identical patterns of lymphoid infiltration and organizing pneumonia. We suggest that GLILD is neither a specific nor a useful entity, and biopsies from CVID and IgAD patients should be diagnosed simply by microscopic pattern(s) observed. The prognosis of CVID with lymphoid infiltrates with or without granulomas in this series was good, contrary to claims in the literature about GLILD.

Abnormal Peyer patch development and B-cell gut homing drive IgA deficiency in Kabuki syndrome.

BACKGROUND: Kabuki syndrome (KS) is commonly caused by mutations in the histone-modifying enzyme lysine methyltransferase 2D (KMT2D). Immune dysfunction is frequently observed in individuals with KS, but the role of KMT2D in immune system function has not been identified. OBJECTIVE: We sought to understand the mechanisms driving KS-associated immune deficiency (hypogammaglobulinemia [low IgA], splenomegaly, and diminished immunization responses). METHODS: We performed a comprehensive evaluation of humoral immunity and secondary lymphoid tissues in an established KS (Kmt2d+/ßGeo) mouse model and validated select findings in a patient with KS. RESULTS: Compared with wild-type littermates, Kmt2d+/ßGeo mice demonstrated deficiencies in multiple B-cell lineages and reduced serum IgA and elevated IgM levels across multiple ages. The bone marrow, spleen, and intestine of Kmt2d+/ßGeo mice contained diminished numbers of IgA-secreting cells, while elevated germinal center B cells were found in the mesenteric lymph node and Peyer patches. Kmt2d+/ßGeo mice have decreased size and numbers of Peyer patches, a finding confirmed in human samples. We identified deficiency of Itgb7 RNA and protein expression, a gene encoding an adhesion protein that mediates intestinal homing, and we demonstrated KMT2D-dependent control of ITGB7 expression in a human cell line. CONCLUSIONS: Kmt2d haploinsufficiency has broad deleterious effects on B-cell differentiation, specifically hampering gut lymphocyte homing and IgA+ plasma cell differentiation. Intestinal lymphoid defects caused by ITGB7 deficiency have not previously been recognized in KS, and these results provide new mechanistic insights into the pathogenesis of KS-associated immune deficiency.

Transient hypogammaglobulinaemia of infancy: many patients recover in adolescence and adulthood.

Transient hypogammaglobulinaemia of infancy (THI) is a relatively rare disorder where there is an exaggeration of the physiological nadir of immunoglobulin (Ig)G between loss of transplacentally acquired maternal IgG and production by the infant. Patients may be vulnerable to infections during the period of hypogammaglobulinaemia. The precise time to recovery in all infants is currently unknown. We sought to determine the clinical features and time-course of recovery for patients with THI. We reviewed our experience with THI over the last three decades in order to describe clinical and laboratory features, as well as the time-course of recovery. Forty-seven patients were identified with THI. Only thirty-seven per cent remitted by 4 years of age, while some patients did not recover until the third or fourth decade. In keeping with previous studies, the majority (25 of 47) presented with recurrent infections, nine had a family history of immunodeficiency and 13 had adverse reactions to food as their dominant clinical manifestation. Chronic tonsillitis developed in 10 patients and symptoms improved following surgery. The group with food allergies recovered sooner than those presenting with infections or with a family history immunodeficiency. Eight patients failed to respond to at least one routine childhood vaccine. Two have IgA deficiency and four individuals recovering in adolescence and adulthood continue to have borderline/low IgG levels. None have progressed to common variable immunodeficiency disorders (CVID). THI is a misnomer, as the majority do not recover in infancy. Recovery from THI can extend into adulthood. THI must be considered in the differential diagnosis of adolescents or young adults presenting with primary hypogammaglobulinemia.

A Systematic Review on Predisposition to Lymphoid (B and T cell) Neoplasias in Patients With Primary Immunodeficiencies and Immune Dysregulatory Disorders (Inborn Errors of Immunity).

Primary immunodeficiencies and immune dysregulatory disorders (PIDDs; now referred to as inborn errors in immunity) are rare disorders with a prevalence of 41. 4 or 50.5 per 100,000 persons (1). The incidence of malignancy in PIDD patents is the second-highest cause of death in children as well as adults, after infection, and is higher in certain PIDDs compared to others. We performed a systematic review of the literature to identify reports of B cell and T cell neoplasias in PIDDs and clustered them based on their classification in the IUIS schema. As would be expected, higher susceptibility to malignancies are typically reported in patients with Common Variable Immunodeficiency (CVID), combined immunodeficiencies affecting cellular immunity, in particular, DNA repair defects, or in the context of impaired immune regulatory control. There is not much evidence of increased risk for cancer in patients with innate immune defects, indicating that not all types of infection or genetic susceptibility predispose equally to cancer risk. Viral infections, in particular EBV, HHV and HPV, have been shown to increase susceptibility to developing cancer, but also patients with defects in immune regulation, such as Autoimmune Lymphoproliferative Syndrome (ALPS), activated p110delta syndrome (APDS type 1) and IL-10 receptor deficiency among others have a higher incidence of neoplastic disease, particularly lymphomas. In fact, lymphomas account for two-thirds of all malignancies reported in PIDD patients (2), with either a combined immunodeficiency or DNA repair defect predominating as the underlying immune defect in one registry, or antibody deficiencies in another (3). The vast majority of lymphomas reported in the context of PIDDs are B cell lymphomas, though T cell lymphomas have been reported in a few studies, and tend to largely be associated with chromosomal breakage disorders (4) or Cartilage Hair Hypoplasia (5). There appears to be a much higher prevalence of T cell lymphomas in patients with secondary immunodeficiencies (6), though this could reflect treatment bias. We reviewed the literature and summarized the reports of B and T cell lymphoma in PIDD patients to survey the current state of knowledge in this area.

Autoantibodies against BAFF, APRIL or IL21 - an alternative pathogenesis for antibody-deficiencies?

BACKGROUND: The ability of anti-cytokine antibodies to play a disease-causing role in the pathogenesis of immunodeficiencies is widely accepted. The aim of this study was to investigate whether autoantibodies against BAFF (important B cell survival signal), APRIL (important plasma cell survival signal), or Interleukin-21 (important cytokine for immunoglobulin class switch) present an alternative mechanism for the development of the following primary antibody deficiencies (PADs): common variable immune deficiency (CVID) or selective IgA deficiency (sIgAD). RESULTS: Two hundred thirty-two sera from patients with PADs were screened for autoantibodies against cytokines by ELISA. Statistical data analysis yielded a significant difference (p < 0.01) between the healthy donor sera and both PAD cohorts. The analysis was deepened by subdividing the patient collective into groups with distinct B cell phenotypes but no significant differences were found. For selected sera with notable high ELISA-read outs functional analysis ensued. Anti-BAFF and anti-APRIL antibodies were further examined by a B cell survival assay, whilst the functional relevance of putative anti-IL-21 autoantibodies was investigated by means of a STAT3 phosphorylation assay. However, the results of these experiments revealed no discernible functional effect. CONCLUSION: Whilst statistical analysis of ELISA results showed significant differences between patients and healthy controls, in our set of patients functional tests yielded no evidence for an involvement of autoantibodies against BAFF, APRIL, or IL-21 in the pathogenesis of CVID or sIgAD.

Ataxia-telangiectasia: Immunodeficiency and survival.

Ataxia-telangiectasia (AT) is a neurodegenerative disorder characterized by ataxia, telangiectasia, and immunodeficiency. An increased risk of malignancies and respiratory diseases dramatically reduce life expectancy. To better counsel families, develop individual follow-up programs, and select patients for therapeutic trials, more knowledge is needed on factors influencing survival. This retrospective cohort study of 61 AT patients shows that classical AT patients had a shorter survival than variant patients (HR 5.9, 95%CI 2.0-17.7), especially once a malignancy was diagnosed (HR 2.5, 95%CI 1.1-5.5, compared to classical AT patients without malignancy). Patients with the hyper IgM phenotype with hypogammaglobulinemia (AT-HIGM) and patients with an IgG2 deficiency showed decreased survival compared to patients with normal IgG (HR 9.2, 95%CI 3.2-26.5) and patients with normal IgG2 levels (HR 7.8, 95%CI 1.7-36.2), respectively. If high risk treatment trials will become available for AT, those patients with factors indicating the poorest prognosis might be considered for inclusion first.

The long and winding road to IgA deficiency: causes and consequences.

INTRODUCTION: The most common humoral immunodeficiency is IgA deficiency. One of the first papers addressing the cellular and molecular mechanisms underlying IgA deficiency indicated that immature IgA-positive B-lymphocytes are present in these patients. This suggests that the genetic background for IgA is still intact and that class switching can take place. At this moment, it cannot be ruled out that genetic as well as environmental factors are involved. Areas covered: A clinical presentation, the biological functions of IgA, and the management of IgA deficiency are reviewed. In some IgA deficient patients, a relationship with a loss-of-function mutation in the TACI (transmembrane activator and calcium-modulating cyclophilin ligand interaction) gene has been found. Many other genes also have been associated. Gut microbiota are an important environmental trigger for IgA synthesis. Expert commentary: Expression of IgA deficiency is due to both genetic and environmental factors and a role for gut microbiota cannot be excluded.

A comparison of B cell subsets in primary immune deficiencies that progress with antibody deficiency and age-matched healthy children.

BACKGROUND: The objective of this study was to examine the B lymphocyte subsets in primary immunodeficiency that progress with antibody deficiency. METHODS: The patients' naive, memory, class-switched memory and non-switched memory B cells were compared with those of healthy individuals of matching ages using flow cytometry. RESULTS: A total of 67 patients with antibody deficiency and 28 healthy children of matching ages were included in the study. The median age of the patients was six years (min-max: 1-24) and 40 (59.7%) were male. The median age of the healthy controls was again six years (min-max: 1-17) and 12 (42.8%) were male. Patients with common variable immunodeficiency had higher relative counts of naive cells when compared with the control group; however, they were found to have lower relative counts of memory, relative and absolute counts of non-switched and relative counts of switched B lymphocytes (p=0.001, 0.023, 0.003-0.003, 0.001, respectively). In patients with selective IgA deficiency, similar to patients with common variable immunodeficiency, the relative counts of naive cells were found to be higher, while the relative counts of memory and relative and absolute counts of non-switched B lymphocytes were found to be lower when compared with the control group (p=0.011, 0.032, 0.006-0.009, respectively). Although patients with selective IgM deficiency had higher relative counts of naive B cells when compared with the control group, they had lower relative and absolute counts of non-switched B lymphocytes (p=0.008-0.016). CONCLUSIONS: The B lymphocyte subsets of patients with selective IgA deficiency are largely similar to those of patients with common variable immunodeficiency. Both illness groups exhibit low levels of memory B cells.

Helicobacter pylori infection in patients with selective immunoglobulin a deficiency.

Selective immunoglobulin A (IgA) deficiency (IgAD) is the most common primary immunodeficiency in the western world. The aim of the study was to investigate the prevalence and clinical characteristics of Helicobacter pylori-infected dyspeptic patients with IgAD. Case samples were drawn from all subjects ≥ 12 years of age (n = 104729) who had undergone serum total IgA measurements during 2004-14 for any reason at Leumit Healthcare Services (Israel) and had serum total IgA < 0·07 g/l. The control group was comprised of a random sample of remaining patients with a case-control ratio of 10 controls for each case. The dyspeptic diseases were identified and retrieved from Leumit Health Care Services electronic database using specific ICD-9-CM diagnostic codes. The case group included 347 subjects and the control group 3470 subjects. There were no significant differences in the prevalence of patients with dyspepsia [84 (24·2%) versus 821 (23·6%) for cases and controls, respectively]. Additionally, there was no difference in a proportion of dyspeptic H. pylori-positive subjects [59 (17·1%) versus 524 (15·1%)] between the case and control groups. Only 59 (17%) among the 347 IgAD patients underwent gastroscopy. A significantly larger proportion of case subjects experienced several forms of gastritis [13 (61·9%) versus 38 (21·6%), P < 0·001), duodenal ulcers [seven (33·3%) versus 19 (10·8%); P = 0·01] and nodular lymphoid hyperplasia (NLH) [two (9·5%) versus none; P = 0·011]. IgAD is not associated with increased prevalence of H. pylori-associated dyspepsia; nevertheless, H. pylori-infected dyspeptic IgAD subjects experience more EGD-proved gastritis, duodenal ulcers and NLH.

Role of apoptosis in common variable immunodeficiency and selective immunoglobulin A deficiency.

Common variable immunodeficiency (CVID) and selective IgA deficiency (SIgAD) are the most common primary immunodeficiencies in human. Both diseases share clinical manifestation and molecular defects. Increased apoptosis may be one of the mechanisms involved in the pathogenesis of CVID and SIgAD. Elevated apoptosis in this disorder leads to defective long-term survival of B-cells, reduced antibody production, decreased lymphocyte proliferation and defective cytokine secretion. For the first time, we reviewed the role of apoptosis in CVID and SIgAD.

Doenças autoimunes e autoanticorpos em pacientes pediátricos e seus parentes de primeiro grau com deficiência de imunoglobulina / Autoimmune diseases and autoantibodies in pediatric patients and their first-degree relatives with immunoglobulin A deficiency

Introdução: As manifestações clínicas da deficiência de imunoglobulina A (DIgA) incluem infecções recorrentes, atopia e doenças autoimunes. No entanto, para o nosso conhecimento, as avaliações concomitantes de doenças autoimunes e autoanticorpos em uma coorte de pacientes com DIgA com idade atual > 10 anos e seus parentes não foram feitas. Objetivos: Avaliar doenças autoimunes e presença de autoanticorpos em pacientes com DIgA e seus parentes de primeiro grau. Métodos: Estudo transversal feito em 34 pacientes com DIgA (idade atual > 10 anos) e em seus parentes de primeiro grau. Todos foram acompanhados em um centro terciário brasileiro para imunodeficiência primária: 27 crianças/adolescentes e sete de seus parentes de primeiro grau com diagnóstico tardio de DIgA. Doenças autoimunes e autoanticorpos (anticorpos antinucleares, fator reumatoide e antitireoglobulina, antitiroperoxidase e anticorpos antiendomísio da classe IgA) também foram avaliadas. Resultados: Doenças autoimunes (n = 14) e/ou autoanticorpos (n = 10, quatro deles com autoanticorpos isolados) foram observadas em 18/34 (53%) dos pacientes e seus parentes. As doenças autoimunes mais comuns encontradas foram tireoidite (18%), artrite crônica (12%) e doença celíaca (6%). Os autoanticorpos mais frequentes foram anticorpos antinucleares (2%), antitireoglobulina e/ou antitireoperoxidase (24%). Nenhuma diferença significativa foi observada no sexo feminino, idade no momento do diagnóstico e idade atual em pacientes com DIgA com e sem doenças autoimunes e/ou presença de autoanticorpos (p > 0,05). As frequências de imunodeficiência de primárias na família, autoimunidade em família, atopia e infecções recorrentes foram semelhantes em ambos os grupos (p> 0,05). Conclusão: Doenças autoimunes e autoanticorpos foram observadas em pacientes com DIgA durante o acompanhamento, o que reforça a necessidade de um acompanhamento rigoroso e contínuo durante a adolescência e a idade adulta. .

Introduction: Clinical manifestations of Immunoglobulin A Deficiency (IgAD) include recur-rent infections, atopy and autoimmune diseases. However, to our knowledge, theconcomitant evaluations of autoimmune diseases and auto antibodies in a cohort of IgADpatients with current age >10 years and their relatives have not been assessed. Objectives: To evaluate autoimmune diseases and the presence of auto antibodies in IgADpatients and their first-degree relatives. Methods: A cross-sectional study was performed in 34 IgAD patients (current age >10years) and their first-degree relatives. All of them were followed at a tertiary Brazilianprimary immunodeficiency center: 27 children/adolescents and 7 of their first-degree rela-tives with a late diagnosis of IgAD. Autoimmune diseases and autoantibodies (antinuclearantibodies, rheumatoid factor, and anti-thyroglobulin, anti-thyroperoxidase and IgA classanti-endomysial antibodies) were also assessed. Results: Autoimmune diseases (n = 14) and/or autoantibodies (n = 10, four of them with iso-lated autoantibodies) were observed in 18/34 (53%) of the patients and their relatives. Themost common autoimmune diseases found were thyroiditis (18%), chronic arthritis (12%)and celiac disease (6%). The most frequent autoantibodies were antinuclear antibodies(2%), anti-thyroglobulin and/or anti-thyroperoxidase (24%). No significant differences wereobserved in the female gender, age at diagnosis and current age in IgAD patients with andwithout autoimmune diseases and/or presence of auto antibodies (p > 0.05). The frequen-cies of primary immunodeficiencies in family, autoimmunity in family, atopy and recurrentinfections were similar in both groups (p > 0.05). Conclusion: Autoimmune diseases and auto antibodies were observed in IgAD patients dur-ing follow-up, reinforcing the necessity of a rigorous and continuous follow-up duringadolescence and adulthood. .

RAG1 deficiency may present clinically as selective IgA deficiency.

BACKGROUND: Recombination-activating gene (RAG) 1 and 2 deficiency is seen in patients with severe combined immunodeficiency (SCID) and Omenn syndrome. However, the spectrum of the disease has recently expanded to include a milder phenotype. OBJECTIVE: We analyzed a 4-year-old boy who was initially given the diagnosis of selective immunoglobulin A deficiency (SIgAD) based on immunoglobulin serum levels without any opportunistic infections, rashes, hepatosplenomegaly, autoimmunity or granulomas. The patient was found to be infected with varicella zoster; however, the clinical course was not serious. He produced antiviral antibodies. METHODS: We performed lymphocyte phenotyping, quantification of T cell receptor excision circles (TRECs) and kappa deleting recombination excision circles (KRECs), an analysis of target sequences of RAG1 and 2, a whole-genome SNP array, an in vitro V(D)J recombination assay, a spectratype analysis of the CDR3 region and a flow cytometric analysis of the bone marrow. RESULTS: Lymphocyte phenotyping demonstrated that the ratio of CD4+ to CD8+ T cells was inverted and the majority of CD4+T cells expressed CD45RO antigens in addition to the almost complete lack of B cells. Furthermore, both TRECs and KRECs were absent. Targeted DNA sequencing and SNP array revealed that the patient carried a deletion of RAG1 and RAG2 genes on the paternally-derived chromosome 11, and two maternally-derived novel RAG1 missense mutations (E455K, R764H). In vitro analysis of recombination activity showed that both RAG1 mutant proteins had low, but residual function. CONCLUSIONS: The current case further expands the phenotypic spectrum of mild presentations of RAG deficiency, and suggests that TRECs and KRECs are useful markers for detecting hidden severe, as well as mild, cases.

Calidad de vida relacionada a salud de niños con deficiencia de IgA sérica respecto de pacientes con otra patología crónica como asma y controles sanos / Health related quality of life from children with serum IgA deficiency compared with other chronic conditions as asthma and healthy controls

Introducción. la calidad de vida relacionada a sakud (CVRS) permite evaluar el bienestar y la capacidad para realizar actividades a partir de la propia percepción individual influenciada por el estado salud-enfermedad. Las patologías crónicas inciden fuertemente en ella. Existen numerosos métodos para evaluarla tanto para niños como para sus padres/cuidadores...

Introduction. health related quality of Life (HRQOL) allows assessment of the well-being and ability to perform activitties from individual perception itself influeced by the health-disease state. Chronic diseases impact strongly about it There are numerous methods to evaluante for both children and their parents/caregivers...

B cells as a critical node in the microbiota-host immune system network.

Mutualism with our intestinal microbiota is a prerequisite for healthy existence. This requires physical separation of the majority of the microbiota from the host (by secreted antimicrobials, mucus, and the intestinal epithelium) and active immune control of the low numbers of microbes that overcome these physical and chemical barriers, even in healthy individuals. In this review, we address how B-cell responses to members of the intestinal microbiota form a robust network with mucus, epithelial integrity, follicular helper T cells, innate immunity, and gut-associated lymphoid tissues to maintain host-microbiota mutualism.

Serological assessment for celiac disease in IgA deficient adults.

PURPOSE: Selective immunoglobulin A deficiency is the most common primary immunodeficiency disorder that is strongly overrepresented among patients with celiac disease (CD). IgG antibodies against tissue transglutaminase (tTG) and deamidated gliadin peptides (DGP) serve as serological markers for CD in IgA deficient individuals, although the diagnostic value remains uncertain. The aim of this study was to investigate the prevalence of these markers in a large cohort of IgA deficient adults with confirmed or suspected CD and relate the findings to gluten free diet. METHODS: Sera from 488,156 individuals were screened for CD in seven Swedish clinical immunology laboratories between 1998 and 2012. In total, 356 out of 1,414 identified IgA deficient adults agreed to participate in this study and were resampled. Forty-seven IgA deficient blood donors served as controls. Analyses of IgG antibodies against tTG and DGP as well as HLA typing were performed and a questionnaire was used to investigate adherence to gluten free diet. Available biopsy results were collected. RESULTS: Out of the 356 IgA deficient resampled adults, 67 (18.8%) were positive for IgG anti-tTG and 79 (22.2%) for IgG anti-DGP, 54 had biopsy confirmed CD. Among the 47 IgA deficient blood donors, 4 (9%) were positive for IgG anti-tTG and 8 (17%) for anti-DGP. Four were diagnosed with biopsy verified CD, however, 2 of the patients were negative for all markers. Sixty-eight of 69 individuals with positive IgG anti-tTG were HLA-DQ2/DQ8 positive whereas 7 (18.9%) of the 37 individuals positive for IgG anti-DGP alone were not. CONCLUSIONS: IgG anti-tTG seems to be a more reliable marker for CD in IgA deficient adults whereas the diagnostic specificity of anti-DGP appears to be lower. High levels of IgG antibodies against tTG and DGP were frequently found in IgA deficient adults despite adhering to gluten free diet.

Clinical evaluation of the BioPlex 2200 Celiac IgA and IgG Kits - a novel multiplex screen incorporating an integral check for IgA deficiency.

INTRODUCTION: Celiac disease screening is commonly based on detection of IgA anti-tissue transglutaminase (TTGA). IgA deficiency (IgAD) is associated with celiac disease and must be identified to enable use of IgG based assays in these patients. The BioPlex® 2200 Celiac IgA and IgG kits use Luminex methodology to provide a method of simultaneously measuring TTG and deamidated gliadin peptide (DGP) antibody levels using a fully automated random access analyzer based on Luminex® technology. Separate kits are available for IgA (TTGA and DGPA) and IgG (TTGG and DGPG) isotypes. The IgA based kit includes a novel "IgA Verification Bead" (AVB) to check for IgAD (at <0.07g/L) to ensure that these patients are identified and tested using the IgG based kit. AIM: To perform a clinical and technical evaluation of the BioPlex® 2200 Celiac IgA and IgG kits. METHODS: 116 sera from 116 biopsy proven celiac disease patients were tested (58 new presentations on a gluten containing diet and 58 known TTGA positive patients on a gluten free diet but with suspected poor compliance). IgAD was present in 5 patients. Ability to flag IgAD sera was assessed by analysis of 29 IgAD and 200 non-IgAD sera. Specificity was calculated from 124 unselected consecutive disease control sera. RESULTS: Sensitivity and specificity for IgAD were 100%. Screening with TTGA and adding TTGG when IgAD was identified, gave clinical sensitivity of 100% for celiac disease. Specificity was 100% for TTGA and TTGG, and 98% and 97% for DGPA and DGPG respectively. CONCLUSION: Use of the BioPlex® 2200 Celiac IgA and Celiac IgG kits in a standard protocol gave excellent sensitivity and specificity with highly effective detection of IgAD, no false positive IgAD flags and little evidence of interference from high IgA levels. The ability to detect IgAD without pre-screening with a separate IgA assay should have a significant beneficial impact on laboratory workflow by identifying those patients requiring IgG based testing and IgA measurement to confirm IgAD.