Selective IgA deficiency in early life: association to infections and allergic diseases during childhood

The Microbiome, Timing, and Barrier Function in the Context of Allergic Disease

Allergic disease affects millions. Despite many advances in our understanding of the immune system in the past century, the physiologic underpinning for the existence of allergy remains largely mysterious. Food allergies, in particular, have increased dramatically in recent years, adding a new sense of urgency to unraveling this mystery. The concurrence of significant lifestyle changes in Western societies with increasing disease prevalence implies a causal link. Demographic variables that influence the composition and function of the commensal microbiota early in life seem to be most important. Identifying the evolutionary and physiologic foundations of allergic disease and defining what about our modern environment is responsible for its increased incidence will provide insights critical to the development of new approaches to prevention and treatment.

Effect of cognitive enrichment on behavior, mucosal immunity and upper respiratory disease of shelter cats rated as frustrated on arrival

Acquisition of resources and opportunity to engage in natural behaviors has been shown to reduce frustration-related behaviors and enhance health in nondomestic felids kept in zoos, but little is known about whether there are similar effects in domestic cats living in confinement in animal shelters. Fifteen cats rated as Frustrated during the first hour of confinement to a cage at an animal shelter were assigned to either a Treatment (n=7) or Control (n=8) group. Treatment cats were taken from their cages to a separate room four times daily for 10min each time over a 10 d period, where they took part in training sessions to learn a novel behavior (paw-hand contact with a researcher). Changes in emotional states and mucosal immune response were evaluated over 10days. Infectious status was determined upon admission and incidence of upper respiratory was determined up to day 40 based on clinical signs. Treated cats were more likely to be rated as Content than Control cats and had greater concentrations of S-IgA (537μg/g) in feces than Control cats (101μg/g). Within the Treatment group, cats that responded positively had greater concentrations of S-IgA (925μg/g) than those that responded negatively (399μg/g). Control cats were more likely to develop respiratory disease over time compared to cats that received treatment (Hazard Ratio: 2.37, Confidence Interval: 1.35-4.15). It is concluded that there is prima facie evidence that cognitive enrichment of cats exhibiting frustration-related behaviors can elicit positive affect (contentment), stimulate secretion of IgA and reduce incidence of respiratory disease, which is worthy of further study.

Food Allergy

Food allergy is receiving increased attention in recent years. Because there is currently no known cure for food allergy, avoiding the offending food is the best defense for sensitive individuals. Type I food allergy is mediated by food proteins, and thus, theoretically, any food protein is a potential allergen. Variability of an individual's immune system further complicates attempts to understand allergen-antibody interaction. In this article, we briefly review food allergy occurrence, prevalence, mechanisms, and detection. Efforts aimed at reducing/eliminating allergens through food processing are discussed. Future research needs are addressed.

Acoustophoretic removal of proteins from blood components

This work presents the development of a miniaturized system for removing plasma proteins and other low-molecular-weight compounds from red blood cell (RBC) concentrate in a simple one-step-process using integrated ultrasound. The technology utilizes the principles of acoustophoresis to transfer the RBCs from the original plasma-containing solution into a protein-free SAG-M additive solution in a continuous flow process. The preparation of protein free RBC concentrate is important for blood transfusion to patients suffering from immunoglobulin A (IgA)-deficiency and developing antibodies against IgA. We show a nearly complete removal of both albumin and IgA from concentrated RBCs via this one-step-processes in samples obtained from RBC concentrate. The cell recovery of our technology is close to 97%, compared to just above 90% of the current procedure of repeated dilution and centrifugation steps. This work clearly shows the potential of integrated acoustophoresis in a miniaturized system for clinical applications.

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.

Raised immunoglobulin A and circulating T follicular helper cells are linked to the development of food allergy in paediatric liver transplant patients

BACKGROUND

Post-transplant food allergy (LTFA) is increasingly observed after paediatric liver transplantation (LT). Although the immunopathology of LTFA remains unclear, immunoglobulin (Ig) E seems to be implicated.

OBJECTIVE

To study humoral and cellular immunity in paediatric LT patients in search for factors associated with LTFA, and compare with healthy controls (HC) and non-transplant food-allergic children (FA).

METHODS

We studied serum Ig levels in 29 LTFA, 43 non-food-allergic LT patients (LTnoFA), 21 FA patients and 36 HC. Serum-specific IgA and IgE against common food allergens in LTFA, IgA1 , IgA2 and joining-chain-containing polymeric IgA (pIgA) were measured. Peripheral blood mononuclear cells were analysed by flow cytometry for B and T cell populations of interest.

RESULTS

Serum IgA and specific IgA were higher in LTFA compared to LTnoFA. LTFA patients had the highest proportion of circulating T follicular helper cells (cTfh). The percentage of cTfh correlated positively with serum IgA. Unique in LTFA was also the significant increase in serum markers of mucosal IgA and the decrease in the Th17 subset of CXCR5(-) CD4(+) cells compared to HC. Both LT patients exhibited a rise in IgA(+) memory B cells and plasmablasts compared to HC and FA.

CONCLUSIONS

LT has an impact on humoral immunity, remarkably in those patients developing FA. The increase in serum markers of mucosal IgA, food allergen-specific IgA and cTfh cells observed in LTFA, point towards a disturbance in intestinal immune homoeostasis in this patient group.

Early Exposure to Respiratory Allergens by Placental Transfer and Breastfeeding

The relationship between allergen exposure and the onset of or protection from allergic diseases remains unclear. Many factors could be related to immunological responses, such as the age when the exposure occurs, type of allergen, timing, dose, and allergen route. In this study, we investigated whether exposure to respiratory allergens could occur in pregnancy or early life. In particular, we assessed whether Der p 1 and Blo t 5, as well as specific antibodies against these allergens, could be detected in 90 paired cord blood and colostrum samples. Der p 1 was detected in 58.6% of colostrum and 29% of cord blood samples, whereas Blot 5 was positive in 41.3% and 9.6% of the samples, respectively. Similar to specific IgA, which could be detected in all samples for both mites, specific IgG was found in a high number of colostrum samples, 93.5% and 94.8% for Dp and Bt, respectively. Although allergens were not detected in all cord blood samples, a high percentage of them (≥95%) were positive for specific IgM to both mites in cord blood samples, suggesting that neonates can be exposed and sensitized to airborne allergens during pregnancy. Many studies have attempted to correlate allergen exposure or its prevention in early infancy with the onset of or protection from allergic diseases. However, conflicting and inconsistent data do not show a clear correlation with or suggest a way to prevent allergen sensitization. Nevertheless, these unconvincing results could be better understood if the relationship with many aspects of allergen exposure after pregnancy could be clarified. Thus, it is necessary to address basic issues related to allergen exposure, including the development of reproducible, standardized and reliable methods, and to determine how and where the exposure occurs.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

[Is familial screening useful in selective immunoglobulin A deficiency?]

INTRODUCTION

Selective immunoglobulin A deficiency (SIgAD), the most common primary immunodeficiency, is often asymptomatic. High rates of familial clustering have been described in SIgAD, but the causative genetic defect and mechanism of inheritance are unknown.

OBJECTIVES

To determine whether familial SIgAD cases show more severe clinical and immunological characteristics than sporadic ones; to investigate the utility of screening first-degree relatives (FDRs) of these patients, and to determine whether symptoms in affected family members are important enough to justify screening.

PATIENTS AND METHODS

Descriptive, cross-sectional study (October 2010-September 2011) of all patients with SIgAD and followed up in our center. Demographic, clinical, and analytical data were reviewed. A familial case was defined as an SIgAD patient with at least one affected FDR.

RESULTS

Of the 130 participants, 42 were SIgAD patients and 88 FDR. There were 13 (31%) familial cases and and 14 (16%) affected FDRs. Six family members had to be analyzed in order to detect one affected one. There were no clinical differences between familial and sporadic SIgAD cases. The percentages of intestinal disease (p=001, OR=9.57, 95%CI 2.59-35.3), hospitalizations (p=045, OR=4.01; 95%CI 1.10-14.67], and need for chronic treatment (p=006, OR=5.5; 95%CI 1.57-19.54) were higher in affected FDRs than in unaffected ones.

CONCLUSIONS

The symptoms were not more severe in familial than sporadic SIgAD cases. Nonetheless, the elevated prevalence of affected FDRs with significant morbidity may justify routine screening of close family members of these patients.

[Autoimmune diseases and autoantibodies in pediatric patients and their first-degree relatives with immunoglobulin A deficiency]

INTRODUCTION

Clinical manifestations of Immunoglobulin A Deficiency (IgAD) include recurrent infections, atopy and autoimmune diseases. However, to our knowledge, the concomitant evaluations of autoimmune diseases and autoantibodies in a cohort of IgAD patients with current age > 10 years-old and their relatives have not been assessed.

OBJECTIVES

To evaluate autoimmune diseases and the presence of autoantibodies in IgAD patients and their first-degree relatives.

METHODS

A cross-sectional study was performed in 34 IgAD patients (current age > 10 years-old) and their first-degree relatives. All of them were followed at a tertiary Brazilian primary immunodeficiency center: 27 children/adolescents and 7 of their first-degree relatives with a late diagnosis of IgAD. Autoimmune diseases and autoantibodies (antinuclear antibodies, rheumatoid factor, and anti-thyroglobulin, anti-thyroperoxidase and IgA class anti-endomysial antibodies) were also assessed.

RESULTS

Autoimmune diseases (n=14) and/or autoantibodies (n=10, four of them with isolated autoantibodies) were observed in 18/34 (53%) of the patients and their relatives. The most 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 were observed in the female gender, age at diagnosis and current age in IgAD patients with and without autoimmune diseases and/or presence of autoantibodies (p>0.05). The frequencies of primary immunodeficiency's in family, autoimmunity in family, atopy and recurrent infections were similar in both groups (p>0.05).

CONCLUSION

Autoimmune diseases and autoantibodies were observed in IgAD patients during follow-up, reinforcing the necessity of a rigorous and continuous follow-up during adolescence and adulthood.

IgA deficiency and risk of cancer: a population-based matched cohort study

PURPOSE

To investigate the risk of cancer in individuals with IgA deficiency compared with the general population.

METHODS

Prospective nationwide population-based cohort study. We identified 2320 individuals with IgA deficiency (IgA levels < 0.07 g/L) diagnosed between 1980 and 2010 in six Swedish university hospitals. Individuals with IgA deficiency were then matched on age, sex, place of residence, and year of diagnosis with up to 10 general population controls (n = 23,130). Through linkage with the Swedish Cancer Register we calculated conditional hazard ratios (HRs) for cancer diagnosed after IgA deficiency diagnosis in patients without a previous cancer diagnosis.

RESULTS

During follow-up, 125 individuals with IgA deficiency (61/10,000 person-years) and 984 controls (47/10,000 person-years) developed cancer (HR 1.31; 95%CI = 1.09-1.58). In cause-specific analyses, we found an increased risk of any gastrointestinal cancer (HR = 1.64; 95%CI = 1.07-2.50), but not for lymphoproliferative malignancy (HR 1.68; 95%CI = 0.89-3.19). Relative risk estimates for overall cancer were very high in the first year of follow-up (overall: HR = 2.80; 95%CI = 1.74-4.49), but failed to reach statistical significance thereafter. IgA deficiency diagnosed in childhood (n = 487) was not associated with overall cancer (HR = 3.26; 0.88-12.03).

CONCLUSIONS

Individuals with IgA deficiency are at a moderately increased risk of cancer, with excess risks of gastrointestinal cancer. This excess risk is highest just after diagnosis suggesting a degree of surveillance bias. Children with IgA deficiency were at no increased risk of cancer but the statistical power was limited in subanalyses.

The higher frequency of IgA deficiency among Swedish twins is not explained by HLA haplotypes

Serum immunoglobulin A (IgA) concentrations were determined in 12 600 adult Swedish twins, applying a high-throughput reverse-phase protein microarray technique. The prevalence of IgA deficiency (IgAD) was found to be 1:241 in monozygotic (MZ) twins and 1:198 in dizygotic (DZ) twins. Hence, the prevalence in twins is markedly elevated as compared with the normal Swedish adult population (1:600). The twins did not show a difference in the frequency of HLA haplotypes in comparison with almost 40 000 healthy Swedish controls. As expected, the risk-conveying HLA alleles A*01, B*08 and DRB1*01 were overrepresented among the IgAD twins and were also associated with significantly lower mean serum IgA concentrations in the twin cohort. In contrast, significantly higher mean IgA concentrations were found among individuals carrying the protective HLA alleles B*07 and DRB1*15. Exome sequencing data from two MZ twin pairs discordant for the deficiency showed no differences between the siblings. Model fitting analyses derived a heritability of 35% and indicate that genetic influences are modestly important for IgAD. The probandwise concordance rates for IgAD were found to be 31% for MZ and 13% for DZ twins.

An 8 minute colorimetric paper-based reverse phase vertical flow serum microarray for screening of hyper IgE syndrome

A reverse phase serum array with the capacity of simultaneous detection in 113 samples was developed and optimized for a vertical flow 8-minute colorimetric assay detecting IgE.

Reversal of Immunoglobulin A Deficiency in Children

PURPOSE

Immunoglobulin A deficiency (IgAD) is the most common primary immunodeficiency in the general population. It is defined as a serum IgA level below or equal to 0.07 g/l with normal IgM and IgG levels in children over the age of 4. However, a few cases of reversal of IgAD at later ages have been observed previously, especially in pediatric patients. This study aimed at investigating the frequency of reversal in a large cohort of children and young adults in order to evaluate the present definition of IgAD.

METHODS

Clinical laboratory records from 654 pediatric IgA deficient patients, 4-13 years of age, were retrieved from five university hospitals in Sweden. Follow up in the children where IgA serum levels had been routinely measured was subsequently performed. In addition, follow up of the IgA-levels was also performed at 4, 8 and 16 years of age in children who were IgA deficient at the age of 4 years in a Swedish population-based birth cohort study in Stockholm (BAMSE).

RESULTS

Nine out of 39 (23.1%) children who were identified as IgAD at 4 years of age subsequently increased their serum IgA level above 0.07 g/L. The average age of reversal was 9.53 ± 2.91 years. In addition, 30 out of the 131 (22.9%) children with serum IgAD when sampled between 5 and 9.99 years of age reversed their serum IgA level with time. The BAMSE follow up study showed a reversal of IgAD noted at 4 years of age in 8 out of 14 IgAD children at 16 years of age (5 at 8 years of age) where 4 were normalized their serum IgA levels while 4 still showed low serum levels of IgA, yet above the level defining IgAD. The results indicate that using 4 years of age, as a cut off for a diagnosis of IgAD may not be appropriate.

CONCLUSIONS

Our findings suggest that a diagnosis of IgAD should not be made before the early teens using 0.07 g/L of IgA in serum as a cut off.

Toll-like receptor 2 as a regulator of oral tolerance in the gastrointestinal tract

Food allergy, other adverse immune responses to foods, inflammatory bowel disease, and eosinophilic esophagitis have become increasingly common in the last 30 years. It has been proposed in the "hygiene hypothesis" that dysregulated immune responses to environmental microbial stimuli may modify the balance between tolerance and sensitization in some patients. Of the pattern recognition receptors that respond to microbial signals, toll-like receptors (TLRs) represent the most investigated group. The relationship between allergy and TLR activation is currently at the frontier of immunology research. Although TLR2 is abundant in the mucosal environment, little is known about the complex relationship between bystander TLR2 activation by the commensal microflora and the processing of oral antigens. This review focuses on recent advances in our understanding of the relationship between TLR2 and oral tolerance, with an emphasis on regulatory T cells, eosinophils, B cells, IgA, intestinal regulation, and commensal microbes.

Profile of the patients who present to immunology outpatient clinics because of frequent infections

AIM

We aimed to determine the rate of primary immune deficiency (PID) among children presenting to our immunology outpatient clinic with a history of frequent infections and with warning signs of primary immune deficiency.

MATERIAL AND METHODS

The files of 232 children aged between 1 and 18 years with warning signs of primary immune deficiency who were referred to our pediatric immunology outpatient clinic with a complaint of frequent infections were selected and evaluated retrospectively.

RESULTS

Thirty-six percent of the subjects were female (n=84) and 64% were male (n=148). PID was found in 72.4% (n=164). The most common diagnosis was selective IgA deficiency (26.3%, n=61). The most common diseases other than primary immune deficiency included reactive airway disease and/or atopy (34.4%, n=22), adenoid vegetation (12.3%, n=8), chronic disease (6.3%, n=4) and periodic fever, aphtous stomatitis and adenopathy (4.6%, n=3). The majortiy of the subjects (90.5%, n=210) presented with a complaint of recurrent upper respiratory tract infection. PID was found in all subjects who had bronchiectasis. The rates of the diagnoses of variable immune deficiency and Bruton agammaglubulinemia (XLA) were found to be significantly higher in the subjects who had lower respiratory tract infection, who were hospitalized because of infection and who had a history of severe infection compared to the subjects who did not have these properties (p<0.05 and p<0.01, respectively). Growth and developmental failure was found with a significantly higher rate in the patients who had a diagnosis of severe combined immune deficiency or hyper IgM compared to the other subjects (p<0.01). No difference was found in the rates of PID between the age groups, but the diagnosis of XLA increased as the age of presentation increased and this was considered an indicator which showed that patients with XLA were being diagnosed in a late period.

CONCLUSIONS

It was found that the rate of diagnosis was considerably high (72.4%), when the subjects who had frequent infections were selected by the warning signs of PID.

IgA deficiency and mortality: a population-based cohort study

IgA deficiency has been linked to increased morbidity but data on mortality is lacking. In this population-based prospective cohort study we examined mortality in patients with IgA deficiency compared with the general population. Through six university hospitals in Sweden we identified 2,495 individuals with IgA deficiency (IgA deficiency ≤0.07 mg/L) diagnosed between 1980 and 2012. Each patient with IgA deficiency was matched on age, sex, place of residence, and year of diagnosis with up to 10 general population controls (n = 24,509). Data on education level and emigration status were obtained from Statistics Sweden. Our main outcome measure was all-cause mortality retrieved from the nationwide Causes of Death Register, which includes >99 % of all deaths in Sweden. We used Cox regression to estimate mortality hazard ratios conditioned on the matching factors and adjusted for education level. During 25,367 person-years of follow-up (median 8.3), there were 260 deaths in the IgA deficiency group versus 1,599 deaths during 257,219 person-years (median 8.6) in the general population controls (102 versus 62 deaths per 10,000 person-years; incidence rate difference, 40, 95%CI 28–53, P < .001). This corresponded to a conditional mortality hazard ratio of 1.8 (95%CI 1.6–2.1, P < .001). Relative mortality varied by follow-up time (P < .001) from a hazard ratio of 3.6 (95%CI 2.5–5.3; P < .001) during the first year to 1.9 (95%CI 1.5–2.4; P < .001) year 1–4; 1.9 (95%CI 1.4–2.4; P < .001) year 5-9; 1.5 (1.0–2.2; P = .054) year 10–14.9; and 1.1 (0.7–1.6; P = .66) year 15–25. Effect modification was also seen by age in each stratum of follow-up time, with higher relative mortality in younger than older patients (P < .001). In conclusion, patients with IgA deficiency are at increased risk of death in the first 10 to 15 years after diagnosis.

IgA measurements in over 12 000 Swedish twins reveal sex differential heritability and regulatory locus near CD30L

In a broad attempt to improve the understanding of the genetic regulation of serum IgA levels, the heritability was estimated in over 12 000 Swedish twins, and a genome-wide association study was conducted in a subsample of 9617. Using the classical twin model the heritability was found to be significantly larger among females (61%) compared with males (21%), while contribution from shared environment (20%) was only seen for males. By modeling the genetic relationship matrix with IgA levels, we estimate that a substantial proportion (31%) of variance in IgA levels can ultimately be explained by the investigated SNPs. The genome-wide association study revealed significant association to two loci: (i) rs6928791 located on chromosome 6, 22 kb upstream of the gene SAM and SH3 domain containing 1 (SASH1) and (ii) rs13300483 on chromosome 9, situated 12 kb downstream the CD30 ligand (CD30L) encoding gene. The association to rs13300483 was replicated in two additional independent Swedish materials. The heritability of IgA levels is moderate and can partly be attributable to common variation in the CD30L locus.

Association between IgA deficiency & other autoimmune conditions: a population-based matched cohort study

PURPOSE

To examine autoimmune disorders in patients with IgA deficiency compared with the general population.

METHODS

Nationwide prospective population-based cohort study. Through six university hospitals in Sweden we identified 2100 individuals with IgA deficiency (IgA levels < .07 g/L) diagnosed between 1980 and 2011. Each patient with IgA deficiency was matched on age, sex, place of residence, and year of diagnosis with up to 10 general population controls (n = 18,653). Data on nine autoimmune disorders were retrieved from the Swedish National Patient Register (including inpatient and non-primary outpatient care). Autoimmune disorders were defined as having at least two visits listing the relevant international classification of disease (ICD) code as main diagnosis. Prevalences and prevalence ratios (PRs) were calculated.

RESULTS

Individuals with IgA deficiency more often had celiac disease (6.7 % vs. 0.19 % in controls) and type 1 diabetes (5.9 % vs. 0.57 %) corresponding to a 35-fold higher PR for celiac disease and 10-fold higher for type 1 diabetes. Also for the other autoimmune diseases did we see statistically significantly elevated prevalences and PRs (juvenile idiopathic arthritis (0.76 % vs. 0.09 % in controls, PR = 8.9), systemic lupus erythematosus (0.57 % vs. 0.06 %; PR = 8.9), inflammatory bowel disease (3.9 % vs. 0.81 %; PR = 5.0; specifically Crohn's disease (2.4 % vs. 0.42 %; PR = 5.7) and ulcerative colitis (1.7 % vs. 0.46 %; PR = 3.9)), hypothyreosis (0.76 % vs. 0.16 %; PR = 4.6), rheumatoid arthritis (2.2 % vs. 0.50 %; PR = 4.5), and hyperthyreosis (1.7 % vs. 0.43 %; PR = 3.9), but not with myasthenia gravis (0.05 % vs. 0.02 %; PR = 3.0).

CONCLUSIONS

Individuals with IgA deficiency have a higher prevalence of several other autoimmune disorders.

The potential link between gut microbiota and IgE-mediated food allergy in early life

There has been a dramatic rise in the prevalence of IgE-mediated food allergy over recent decades, particularly among infants and young children. The cause of this increase is unknown but one putative factor is a change in the composition, richness and balance of the microbiota that colonize the human gut during early infancy. The coevolution of the human gastrointestinal tract and commensal microbiota has resulted in a symbiotic relationship in which gut microbiota play a vital role in early life immune development and function, as well as maintenance of gut wall epithelial integrity. Since IgE mediated food allergy is associated with immune dysregulation and impaired gut epithelial integrity there is substantial interest in the potential link between gut microbiota and food allergy. Although the exact link between gut microbiota and food allergy is yet to be established in humans, recent experimental evidence suggests that specific patterns of gut microbiota colonization may influence the risk and manifestations of food allergy. An understanding of the relationship between gut microbiota and food allergy has the potential to inform both the prevention and treatment of food allergy. In this paper we review the theory and evidence linking gut microbiota and IgE-mediated food allergy in early life. We then consider the implications and challenges for future research, including the techniques of measuring and analyzing gut microbiota, and the types of studies required to advance knowledge in the field.

Tissue transglutaminase antibody levels predict IgA deficiency

OBJECTIVE

Measuring serum tissue transglutaminase immunoglobulin A (tTG IgA) levels is the most widely used screening test for coeliac disease. However, given an increased prevalence of IgA deficiency among coeliac patients there is a risk of false negative results. Hence, in addition to specific serum tTG IgA, screening tests frequently include total IgA levels. The objective of this study was to determine whether tTG IgA antibody levels might be used to predict IgA deficiency and hence avoid unnecessary testing of total IgA levels in all individuals.

DESIGN

Retrospective analysis of 9429 serum tTG IgA and corresponding total IgA levels obtained from children and young adults in the East of England between 2007 and 2011.

RESULTS

The overall prevalence of IgA deficiency was found to be very low with only 0.9% of individuals affected. Using receiver operating characteristic curve analysis we identified a cut-off value for tTG IgA of ≥0.10 μ/mL to be predictive for the absence of total IgA deficiency (IgA<0.06 g/L). Specifically, using this cut-off value, total IgA deficiency could be excluded with a sensitivity of 0.92 and specificity of 0.84. In our cohort, only 16.4% of our patient sample would have needed total IgA measurement to rule out a false negative result due to IgA deficiency.

CONCLUSIONS

Our data provide a simple means of avoiding unnecessary total IgA measurements in the assessment of coeliac disease. By using tTG IgA value quantitatively, only values <0.10 μ/mL require total IgA measurements to rule out IgA deficiency and hence a potentially false negative screening result.

A fresh look at the hygiene hypothesis: how intestinal microbial exposure drives immune effector responses in atopic disease

There currently is no consensus on which immunological mechanisms can best explain the rise in atopic disease post industrialization. The hygiene hypothesis lays groundwork for our understanding of how altered microbial exposures can drive atopy; yet since its introduction increasing evidence suggests the exposure of our immune system to the intestinal microbiota plays a key role in development of atopic disease. As societal change shifts our microbial exposure, concordant shifts in the tolerant and effector functions of our immune systems give rise to more hypersensitive responses to external antigens. This is contrasted with the greater immune tolerant capabilities of individuals still living in regions with lifestyles more representative of our evolutionary history. Recent findings, buoyed by technological advances in the field, suggest a direct role for the intestinal microbiota-immune system interplay in the development of atopic disease mechanisms. Overall, harnessing current mechanistic studies for translational research into microbiota composition and function in relation to atopy have potential for the design of therapeutics that could moderate these diseases.

IgA deficiency and autoimmunity

IgA is the most abundant immunoglobulin in the human body, and performs a very specialized role which involves mucosal immunity, development of tolerance and protection against infection. IgA is the key immunoglobulin in the respiratory and gastrointestinal tracts, which provide the most intimate interface between the environment and self. Normal levels of IgA are based on early studies consisting of only small numbers of patients. The international consensus definition of IgA deficiency is a level of 0.07g/l after the age of four years in the absence of IgG and IgM deficiencies. The epidemiology of IgA deficiency reveals interesting variances between geographical regions - the incidence in Caucasians being much higher than that in Asians. IgA deficiency has also been found to co-exist with autoimmune diseases, allergies and malignancies. The association with autoimmunity is particularly interesting because it suggests a common genetic linkage that could potentially also explain the diversity in geoepidemiology. Both MHC and non-MHC associations have been described and the 8.1 haplotype has been significantly associated with autoimmunity in IgA deficiency patients over controls. Non-MHC genetic associations include IFIH1 and CLEC16A. The mutations leading to IgA deficiency have not been defined, but in some cases of IgA deficiency it has been suggested that the pathogenesis involves a failure in switched memory B cells that can lead to this cohort experiencing an increased incidence of recurrent bacterial infections or autoimmune diseases. Attempts to investigate the role of cytokines that can induce IgA synthesis in cells of patients with IgA deficiency, such as IL21 or the combination of CD40L/anti-CD40, IL-4 and IL10, are underway.

Mucosal immunity and the onset of allergic disease

Mucosal barriers encounter an environment that is rich in pathogens that possess mechanisms for invading mucosal tissues. These barriers also encounter innocuous antigens, such as foods, airborne antigens, and microbiota. The mucosa has developed a sophisticated immune system that can mount robust immune responses against pathogenic antigens, while maintaining mucosal tolerance against non-pathogenic antigens. Accumulating evidence indicates that the mucosal epithelium, dendritic cells, and a subtype of T cells with regulatory properties play important roles in the development and maintenance of mucosal tolerance. Moreover, the micribiota also contribute to regulating the mucosal immune system. A failure to develop or the breakdown of mucosal tolerance can result in allergic diseases, such as food allergy and asthma. By taking advantage of the unique characteristics of the mucosal immune system, strategies that induce regulatory cells in vivo and, thereby, reconstitute mucosal tolerance may be used to develop novel therapies that are suitable for treating or preventing of allergic diseases.

Diarrheal Illness in the Pediatric Population: A Review of Neonatal Enteropathies and Childhood Idiopathic Inflammatory Bowel Disease

In the clinical context of pediatric diarrheal illness, the interpretation of endoscopic mucosal biopsies varies significantly from that in adults. This review outlines these differences by first describing a host of diarrheal illnesses that are nearly exclusive to the pediatric age group. The final portion of this article describes salient pathologic differences between adult and pediatric idiopathic inflammatory bowel disease. The goal of this review is to provide a brief description of each disease process and focus on practical aspects of diagnosis that are applicable for pathologists working in general practice settings.

Multi-faceted functions of secretory IgA at mucosal surfaces

Secretory IgA (SIgA) plays an important role in the protection and homeostatic regulation of intestinal, respiratory, and urogenital mucosal epithelia separating the outside environment from the inside of the body. This primary function of SIgA is referred to as immune exclusion, a process that limits the access of numerous microorganisms and mucosal antigens to these thin and vulnerable mucosal barriers. SIgA has been shown to be involved in avoiding opportunistic pathogens to enter and disseminate in the systemic compartment, as well as tightly controlling the necessary symbiotic relationship existing between commensals and the host. Clearance by peristalsis appears thus as one of the numerous mechanisms whereby SIgA fulfills its function at mucosal surfaces. Sampling of antigen-SIgA complexes by microfold (M) cells, intimate contact occurring with Peyer’s patch dendritic cells (DC), down-regulation of inflammatory processes, modulation of epithelial, and DC responsiveness are some of the recently identified processes to which the contribution of SIgA has been underscored. This review aims at presenting, with emphasis at the biochemical level, how the molecular complexity of SIgA can serve these multiple and non-redundant modes of action.

Controversies in IgG replacement therapy in patients with antibody deficiency diseases

This Current perspectives article will review and highlight the importance of accurate diagnosis of patients who have failed to produce specific antibodies to naturally encountered foreign proteins or polysaccharides or after vaccination and the appropriate institution of immunoglobulin replacement therapy. The field of primary immunodeficiency disease (PIDD) has expanded remarkably since the early descriptions 6 decades ago. With greater recognition and advanced cellular and molecular diagnostic technology, new entities and single-gene defects in patients with PIDD are rapidly being defined. This, combined with treatment advances and newborn screening for severe combined immunodeficiency, has resulted in improved outcomes and survival and even permanent cures. Awareness of PIDD has also increased, but the guidelines for recognition remain to be validated. The zeal for registering and enrolling patients has potentially created a large body of "patients" treated with immunoglobulin replacement unnecessarily. The complexity, diversity, and availability of laboratory testing have brought awareness of PIDD to the forefront, but because of an absence of standardization of certain assays, concerns about the correct diagnosis and appropriate treatment have increased. We hope to refocus the discussion on identifying clear laboratory and clinical guidelines for the establishment of an accurate diagnosis of antibody deficiency, its rationale, and, where indicated, institution of safe treatment.

Screening for coeliac disease in preschool Greek children: the feasibility study of a community-based project

AIM

Evaluation of the prevalence of coeliac disease (CD) in Greek paediatric population.

METHODS

The project consists of two parts: (i) a pilot study of preschool children aged 2-6 years to test the feasibility and diagnostic accuracy of community-based screening and (ii) a CD prevalence study, by random clustered sampling and proportionate stratification of various geographical areas in Greece. Trained nonmedical staff performed a rapid immunochromatographic test to detect IgA antibodies to tTG-IgA and IgA deficiency. Toddlers with positive results were referred to a paediatric gastroenterologist for further assessment with serum anti-tTG IgA and EMA-IgA. Children with positive serum anti-tTG and anti-EMA underwent upper gastrointestinal tract endoscopy and small bowel biopsy and were subsequently in gluten-free diet.

RESULTS

In this project participated 1136 toddlers, who were tested at school. The prevalence of positive rapid anti-tTG screening was 1:154, of IgA deficiency 1:120 and of biopsy-proven CD 1:154. The prevalence of CD from this pilot study served as expected prevalence value for sample size calculation for the main prevalence study.

CONCLUSION

This protocol using rapid immunochromatographic test for the detection of both IgA deficiency and CD is easy to be performed by nonmedical staff in a community setting, enabling the accurate identification of new CD cases among asymptomatic population.

Immunological response in egg-sensitive adults challenged with cheese containing or not containing lysozyme

OBJECTIVE

Lysozyme is an enzyme that hydrolyzes bacterial peptidoglicans. For this reason, it is used in cheese manufacturing in order to prevent a defect of long-ripened hard cheese called "late blowing" due to the outgrowth of spores of Clostridium tyrobutyricum and Clostridium butyricum. Moreover, germination of Listeria monocytogenes spores into vegetative cells is also sensitive to lysozyme. The enzyme can be an allergenic molecule, and for this reason there are concerns about its use in food industry. The immunological and clinical response of consumption of lysozyme-containing cheese has been evaluated in 25 egg-sensitive subjects with or without lysozyme sensitization.

METHODS

A total of 25 egg-sensitive subjects were enrolled in this study. All the subjects were already treated for egg-sensitization and presented a positive skin prick test. All the subjects had a body mass index ≤ 25 kg/m(2) and were in the age range of 20-50 years. Each subject was studied twice and received randomly 30 g of Grana Padano (containing lysozyme) or TrentinGrana cheese (lysozyme-free) of two different aging periods: 16 or 24 months. A washout period of 1 week between each cheese intake was adopted. Blood samples were taken in fasting conditions and 1 hour after cheese intake and IgA, total IgE, and lysozyme-, ovomucoid-, and ovalbumin-specific IgE were measured.

RESULTS

No adverse reactions were observed in both groups of patients after cheese samples were given. Lysozyme did not determine any variation of specific IgE compared with basal level. In lysozyme-sensitive patients a significant relationship between IgA and lysozyme-specific IgE was observed when lysozyme-containing cheese was given, confirming that lysozyme can pass the gut barrier.

CONCLUSIONS

Neither adverse events nor immunological responses were observed after ingestion of cheese containing lysozyme. However, the immunological properties of peptides deriving from cheese protein hydrolysis need to be clarified, as does the effect of lysozyme on bacterial proteolytic activity.

Genome-wide analysis in German shepherd dogs reveals association of a locus on CFA 27 with atopic dermatitis

Humans and dogs are both affected by the allergic skin disease atopic dermatitis (AD), caused by an interaction between genetic and environmental factors. The German shepherd dog (GSD) is a high-risk breed for canine AD (CAD). In this study, we used a Swedish cohort of GSDs as a model for human AD. Serum IgA levels are known to be lower in GSDs compared to other breeds. We detected significantly lower IgA levels in the CAD cases compared to controls (p = 1.1 × 10(-5)) in our study population. We also detected a separation within the GSD cohort, where dogs could be grouped into two different subpopulations. Disease prevalence differed significantly between the subpopulations contributing to population stratification (λ = 1.3), which was successfully corrected for using a mixed model approach. A genome-wide association analysis of CAD was performed (n cases = 91, n controls = 88). IgA levels were included in the model, due to the high correlation between CAD and low IgA levels. In addition, we detected a correlation between IgA levels and the age at the time of sampling (corr = 0.42, p = 3.0 × 10(-9)), thus age was included in the model. A genome-wide significant association was detected on chromosome 27 (praw = 3.1 × 10(-7), pgenome = 0.03). The total associated region was defined as a ~1.5-Mb-long haplotype including eight genes. Through targeted re-sequencing and additional genotyping of a subset of identified SNPs, we defined 11 smaller haplotype blocks within the associated region. Two blocks showed the strongest association to CAD. The ~209-kb region, defined by the two blocks, harbors only the PKP2 gene, encoding Plakophilin 2 expressed in the desmosomes and important for skin structure. Our results may yield further insight into the genetics behind both canine and human AD.

Primary immunodeficiency diseases in different age groups: a report on 1,008 cases from a single Brazilian reference center

Primary immunodeficiencies (PIDs) represent a large group of diseases that affect all age groups. Although PIDs have been recognized as rare diseases, there is epidemiological evidence suggesting that their real prevalence has been underestimated. We performed an evaluation of a series of 1,008 infants, children, adolescents and adults with well-defined PIDs from a single Brazilian center, regarding age at diagnosis, gender and PID category according to the International Union of Immunological Societies classification. Antibody deficiencies were the most common category in the whole series (61 %) for all age groups, with the exception of <2-year-old patients (only 15 %). In the >30-year-old group, antibody deficiencies comprised 84 % of the diagnoses, mostly consisting of common variable immunodeficiency, IgA deficiency and IgM deficiency. Combined immunodeficiencies represented the most frequent category in <2-years-old patients. Most congenital defects of phagocytes were identified in patients <5 -years of age, as were the diseases of immune dysregulation, with the exception of APECED. DiGeorge syndrome and ataxia-telangiectasia were the most frequent entities in the category of well-defined syndromes, which were mostly identified in patients <10-years of age. Males represented three-quarters and two-thirds of <2 -years-old and 2-5-years -old patients, respectively, whereas females predominated among the >30-year-old patients. Our data indicated that some PIDs were only detected at early ages, likely because affected patients do not survive long. In addition, our data pointed out that different strategies should be used to search for PIDs in infants and young children as compared to older patients.

Mucosal antibodies in the regulation of tolerance and allergy to foods

The intestinal mucosa is densely packed with antibody-secreting B cells, the majority of which produce IgA. Mucosal antibodies have traditionally been thought of as neutralizing antibodies that exclude antigens, but they also function in antigen sampling, allowing for selective transcytosis of antigens from the intestinal lumen. IgE-mediated antigen uptake can facilitate the development of allergic reactions to foods, but emerging evidence indicates that IgG-mediated antigen uptake may also play an important role in the development of immune tolerance to foods, particularly in the neonate. This review will focus on the role of intestinal immunoglobulins in the development of clinical tolerance and allergy to food antigens.

Unmedicated, remitted patients with major depression have decreased serum immunoglobulin A

Patents with major depression have evidence of a proinflammatory state with consistent elevations in acute phase proteins and in the levels of inflammatory mediators such as interleukin-6 and tumor necrosis factor-α. We report here a study of the serum levels of immunoglobulin A (IgA) in medication-free patients with major depression in the remitted state (ruMDD). Selective IgA deficiency is the most common form of immunoglobulin abnormality, and is often associated with a higher than expected incidence of proinflammatory and autoimmune phenomena. We measured serum IgG, IgM, and IgA in 28 ruMDD patients and 27 healthy subjects (Ctrl) at 0 (pretreatment), 7, and 24h following sham depletion and tryptophan (TrpD) depletion conducted at least 8 days apart under balanced, randomized, blinded conditions. Immunoglobulins were measured by automated immunonephelometry. Data were analyzed by repeated measures ANOVA with diagnosis as a fixed effect and drug (TrpD vs. sham), and time as repeated measures factors. Serum IgA was consistently lower in ruMDD patients vs. Ctrl at all time points examined (p<0.04 for main effect of diagnosis). Serum IgG and IgM levels did not show significant differences by diagnosis. Medication-free patients with major depression in the remitted state have a significant reduction in serum IgA levels measured on multiple occasions. In the light of the fact that IgA serves many immunomodulatory, anti-inflammatory roles, this finding supports the concept that major depressive illness represents a proinflammatory state.

[Clinical phenotypes associated with selective IgA deficiency: a review of 330 cases and a proposed follow-up protocol]

Selective IgA deficiency is the most common Primary Immune Deficiency. Only a small proportion of these patients present during childhood, but this proportion increases over the years, and may be associated with an IgG subclass deficiency with increased susceptibility to respiratory and digestive tract infections. During childhood, IgA deficient patients may also refer to symptoms related to allergic and autoimmune diseases or tumours.

AIMS

To describe the relationship of selective IgA deficiency with infections, allergic diseases, autoimmune disorders and tumours. To investigate the presence of other immune disorders associated with selective IgA deficiency. To suggest a follow-up protocol for these patients.

METHODS

Retrospective study of paediatric patients (<18 years) being followed-up in the Clinical Immunology Department between 1992 and 2007, as well as laboratory records with IgA values below 50mg/L. Clinical records were reviewed (frequency and intensity of diseases associated with selective IgA deficiency) along with immunology tests performed.

RESULTS

A total of 330 paediatric patients were identified with a selective IgA deficiency: 39 (11.8%) suffered from recurrent ear infections (2 developed secondary deafness), 58 (17.5%) from recurrent upper respiratory tract infections, and 20 patients (6%) from recurrent pneumonia, 6 of whom developed secondary bronchiectasis and 2 underwent a lobectomy. A relationship with atopic disease was found in 62 (18.78%) of patients. Regarding digestive disorders, chronic diarrhoea was found in 21 (6.5%), coeliac disease in 22 (6.6%), and persistently high plasma transaminases in 3. Autoimmune manifestations were found in 38 (11.5%), juvenile chronic arthritis, type 1 diabetes, vitiligo, cytopenia, and Crohn's disease, amongst others). Tumours were identified in 5 (1.5%). An IgG sub-class deficiency was found in 5 patients (4%), and 6 patients had a confirmed deficiency in antibody production.

CONCLUSIONS

In our cohort, 56.6% of patients with IgA deficiency showed other comorbidities which were, in decreasing frequency: recurrent infections (respiratory and ear infections), allergic diseases, autoimmunity and tumours. Some patients will develop a more severe humoral defect (IgG subclass deficiency with or without antibody deficiency).

Children with partial IgA deficiency: clinical characteristics observed in the pediatric rheumatology clinic

Literature is lacking on partial IgA deficiency. In this study, the authors propose to describe the clinical manifestations of patients with partial IgA deficiency. Methods. The authors conducted a retrospective chart review of 13 patients with partial IgA deficiency followed at the pediatric rheumatology clinic at Robert Wood Johnson Medical School. They looked for the presence of rashes, joint pain, joint swelling, and morning stiffness. The authors also examined charts for a history of frequent infections, allergies, and the presence of elevated antinuclear antibody. Results. Eleven out of the 13 patients complained of joint pain, joint swelling, or morning stiffness. Six patients carried a diagnosis of a definitive rheumatic disease. Four patients suffered from frequent infections and 2 patients reported allergies. Conclusion. Partial IgA deficiency appears to be associated with rheumatic diseases and complaints of joint pain, joint swelling, and morning stiffness. A larger study is needed to confirm these results.