Celiac Disease: Promising Biomarkers for Follow-Up

Celiac disease is a common gastroenterological illness. Current diagnostics of the disease are based on serological markers and histology of duodenal biopsies. Hitherto, a strict gluten-free diet is the only effective treatment and is necessary for good control of the disease. Serological tests in current use have very high specificity and sensitivity for diagnostics, but in follow-up they have some limitations. Their levels do not accurately reflect mucosal healing, and they are unable to detect minimal transgressions in the diet. This problem is significant in patients with IgA deficiency, and there exist no robust follow-up tools for monitoring these patients' adherence to treatment. For their follow-up, we currently use IgG-based tests, and these antibodies persist for a long time even when a patient has stopped consuming gluten. More accurate and specific biomarkers are definitely needed. Adherence to a gluten-free diet is essential not only for intestinal mucosa healing and alleviation of symptoms but also for preventing complications associated with celiac disease. Here, we summarize current evidence regarding noninvasive biomarkers potentially useful for follow-up not only of patients with IgA deficiency but for all patients with celiac disease. We describe several very promising biomarkers with potential to be part of clinical practice in the near future.

Serum anti-tissue transglutaminase IgA and prediction of duodenal villous atrophy in adults with suspected coeliac disease without IgA deficiency (Bi.A.CeD): a multicentre, prospective cohort study

BACKGROUND

Whether coeliac disease in adults can be diagnosed with serology alone remains controversial. We aimed to evaluate the accuracy of serum anti-tissue transglutaminase IgA (tTG-IgA) in the diagnosis of coeliac disease.

METHODS

In this multicentre, prospective cohort study, adult participants (aged ≥18 years) with suspected coeliac disease without IgA deficiency who were not on a gluten-free diet and who had a local serum tTG-IgA measurement, were enrolled from Feb 27, 2018, to Dec 24, 2020, by 14 tertiary referral centres (ten from Europe, two from Asia, one from Oceania, and one from South America) to undergo local endoscopic duodenal biopsy. Local serum tTG-IgA was measured with 14 different test brands and concentration expressed as a multiple of each test's upper limit of normal (ULN), and defined as positive when greater than 1 times the ULN. The main study outcome was the reliability of serum tests for the diagnosis of coeliac disease, as defined by duodenal villous atrophy (Marsh type 3 or Corazza-Villanacci grade B). Histology was evaluated by the local pathologist, with discordant cases (positive tTG-IgA without duodenal villous atrophy or negative tTG-IgA with duodenal villous atrophy) re-evaluated by a central pathologist. The reliability of serum tests for the prediction of duodenal villous atrophy was evaluated according to sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve (AUC) for categorical and continuous data.

FINDINGS

We enrolled 436 participants with complete local data on serum tTG-IgA and duodenal histology (296 [68%] women and 140 [32%] men; mean age 40 years [SD 15]). Positive serum tTG-IgA was detected in 363 (83%) participants and negative serum tTG-IgA in 73 (17%). Of the 363 participants with positive serum tTG-IgA, 341 had positive histology (true positives) and 22 had negative histology (false positives) after local review. Of the 73 participants with negative serum tTG-IgA, seven had positive histology (false negatives) and 66 had negative histology (true negatives) after local review. The positive predictive value was 93·9% (95% CI 89·2-98·6), the negative predictive value was 90·4% (85·5-95·3), sensitivity was 98·0% (95·3-100·0), and specificity was 75·0% (66·6-83·4). After central re-evaluation of duodenal histology in 29 discordant cases, there were 348 true positive cases, 15 false positive cases, 66 true negative cases, and seven false negative cases, resulting in a positive predictive value of 95·9% (92·0-99·8), a negative predictive value of 90·4% (85·5-95·3), a sensitivity of 98·0% (95·3-100·0), and a specificity of 81·5% (73·9-89·1). Either using the local or central definition of duodenal histology, the positive predictive value of local serum tTG-IgA increased when the serological threshold was defined at increasing multiples of the ULN (p<0·0001). The AUC for serum tTG-IgA for the prediction of duodenal villous atrophy was 0·87 (95% CI 0·81-0·92) when applying the categorical definition of serum tTG-IgA (positive [>1 × ULN] vs negative [≤1 × ULN]), and 0·93 (0·89-0·96) when applying the numerical definition of serum tTG-IgA (multiples of the ULN). Additional endoscopic findings included peptic gastritis (nine patients), autoimmune atrophic gastritis (three), reflux oesophagitis (31), gastric or duodenal ulcer (three), and Barrett's oesophagus (one). In the 1-year follow-up, a midgut ileum lymphoma was diagnosed in a woman on a gluten-free diet.

INTERPRETATION

Our data showed that biopsy could be reasonably avoided in the diagnosis of coeliac disease in adults with reliable suspicion of coeliac disease and high serum tTG-IgA.

FUNDING

None.

Intestinal Candida albicans overgrowth in IgA deficiency

BACKGROUND

Secretory IgA interacts with commensal bacteria, but its impact on human mycobiota ecology has not been widely explored. In particular, whether human IgA-deficiency is associated with gut fungal dysbiosis remains unknown.

OBJECTIVES

Our goal was to study the impact of IgA on gut mycobiota ecology.

METHODS

The Fungi-Flow method was used to characterize fecal, systemic, and maternal IgA, IgM, and IgG responses against 14 representative fungal strains (yeast/spores or hyphae forms) in healthy donors (HDs) (n = 34, 31, and 20, respectively) and to also compare gut mycobiota opsonization by secretory antibodies in HDs (n = 28) and patients with selective IgA deficiency (SIgAd) (n = 12). Stool mycobiota composition was determined by internal transcribed spacer gene sequencing in HDs (n = 23) and patients with SIgAd (n = 17). Circulating CD4+ T-cell cytokine secretion profiles were determined by intracellular staining. The impact of secretory IgA, purified from breast milk (n = 9), on Candidaalbicans growth and intestinal Caco-2 cell invasion was tested in vitro.

RESULTS

Homeostatic IgA binds commensal fungi with a body fluid-selective pattern of recognition. In patients with SIgAd, fungal gut ecology is preserved by compensatory IgM binding to commensal fungi. Gut Calbicans overgrowth nevertheless occurs in this condition but only in clinically symptomatic patients with decreased TH17/TH22 T-cell responses. Indeed, secretory IgA can reduce in vitro budding and invasion of intestinal cells by Calbicans and therefore exert control on this pathobiont.

CONCLUSION

IgA has a selective impact on Calbicans ecology to preserve fungal-host mutualism.

Selective IgA Deficiency in Spontaneously Hypertensive Rats With Gut Dysbiosis

BACKGROUND

The spontaneously hypertensive rat (SHR) is extensively used to study hypertension. Gut microbiota dysbiosis is a notable feature in SHR for reasons unknown. Immunoglobulin A (IgA) is a major host factor required for gut microbiota homeostasis. We hypothesized that inadequate IgA contributes to gut microbiota dysbiosis in SHR.

METHODS

IgA was measured in feces, cecum, serum, liver, gut-associated lymphoid tissue, and milk from SHR and Wistar Kyoto rats. IgA regulatory factors like IgM, IgG, and pIgR (polymeric immunoglobulin receptor) were analyzed. IgA and IgG antibodies and blood pressure (BP) were measured before and after administrating a bacterial antigen (ie, flagellin).

RESULTS

Compared with Wistar Kyoto rats, SHR displayed remarkably near-deficient IgA levels accompanied by compensatory increases in serum IgM and IgG and gut-liver pIgR expression. Inadequate milk IgA in SHR emphasized this immune defect stemmed from the neonatal stage. Reduced IgA+ B cells in circulation and Peyer patches indicated a possible reason for the lower IgA in SHR. Noteworthy, a genetic insufficiency was unlikely because administering flagellin to SHR induced anti-flagellin IgA antibodies. This immune response surprisingly accelerated hypertension development in SHR, suggesting IgA quiescence may help maintain lower BP.

CONCLUSIONS

This study is the first to reveal IgA deficiency in SHR as one host factor associated with gut microbiota dysbiosis and invigorates future research to determine the pathophysiological role of IgA in hypertension.

Low quality antibody responses in critically ill patients hospitalized with pandemic influenza A(H1N1)pdm09 virus infection

Although some adults infected with influenza 2009 A(H1N1)pdm09 viruses mounted high hemagglutination inhibition (HAI) antibody response, they still suffered from severe disease, or even death. Here, we analyzed antibody profiles in patients (n = 31, 17-65 years) admitted to intensive care units (ICUs) with lung failure and invasive mechanical ventilation use due to infection with A(H1N1)pdm09 viruses during 2009-2011. We performed a comprehensive analysis of the quality and quantity of antibody responses using HAI, virus neutralization, biolayer interferometry, enzyme-linked-lectin and enzyme-linked immunosorbent assays. At time of the ICU admission, 45% (14/31) of the patients had HAI antibody titers ≥ 80 in the first serum (S1), most (13/14) exhibited narrowly-focused HAI and/or anti-HA-head binding antibodies targeting single epitopes in or around the receptor binding site. In contrast, 42% (13/31) of the patients with HAI titers ≤ 10 in S1 had non-neutralizing anti-HA-stem antibodies against A(H1N1)pdm09 viruses. Only 19% (6/31) of the patients showed HA-specific IgG1-dominant antibody responses. Three of 5 fatal patients possessed highly focused cross-type HAI antibodies targeting the (K130 + Q223)-epitopes with extremely low avidity. Our findings suggest that narrowly-focused low-quality antibody responses targeting specific HA-epitopes may have contributed to severe infection of the lower respiratory tract.

Protocols of Standard of Care for Adult Patients with Primary Antibody Deficiencies Will Improve Timing of Diagnosis, Survival, and Quality of Life

The majority of primary immunodeficiencies (PIDs) are antibody deficiencies (PADs), and not all of them are rare diseases; As an example, Caucasian individuals suffer from selective IgA deficiency at a frequency of 1:500. In addition to infections, symptomatic patients with PAD are more likely to develop neoplastic, autoimmune, and allergic diseases. In the event that PAD is neglected or delayed for more than ten years, complications develop, eventually resulting in death. No studies have been conducted to devise and report detailed ready-to-use protocols for managing PAD to date. This study aimed to propose protocols and guidelines for the adult PAD patients' standard care. Preparing the protocol, we considered the frequency and type of laboratory tests, imaging, endoscopic examinations, specialist consultations, and standardized recommendations for further care in the place of residence.  As a result of the proposed monitoring scheme, patients can be provided with complete care in terms of their underlying conditions and comorbidities, as well as early detection of complications. This protocol will serve as a guide for physicians dealing with these patients and enable comparisons of patient groups across a variety of treatment centers, even far away from each other. A national consultant in the field of clinical immunology verified the protocol mainly developed by Polish experts from reference immunology centres for adults.

Protocol for the unclassified primary antibody deficiency (unPAD) study: Characterization and classification of patients using the ESID online Registry

Background

Primary antibody deficiencies (PADs) without an identified monogenetic origin form the largest and most heterogeneous group of primary immunodeficiencies. These patients often remain undiagnosed for years and many present to medical attention in adulthood after several infections risking structural complications. Not much is known about their treatment, comorbidities, or prognosis, nor whether the various immunological forms (decreased total IgG, IgG subclass(es), IgM, IgA, specific antibody responses, alone or in combination(s)) should be considered as separate, clearly definable subgroups. The unclassified primary antibody deficiency (unPAD) study aims to describe in detail all PAD patients without an identified specific monogenetic defect regarding their demographical, clinical, and immunological characteristics at presentation and during follow-up. In constructing these patterns, the unPAD study aims to reduce the number of missed and unidentified PAD patients in the future. In addition, this study will focus on subclassifying unPAD to support the identification of patients at higher risk for infection or immune dysregulation related complications, enabling the development of personalized follow-up and treatment plans.

Methods and analysis

We present a protocol for a multicenter observational cohort study using the ESID online Registry. Patients of all ages who have given informed consent for participation in the ESID online Registry and fulfill the ESID Clinical Working Definitions for ‘unclassified antibody deficiency’, ‘deficiency of specific IgG’, ‘IgA with IgG subclass deficiency’, ‘isolated IgG subclass deficiency’, ‘selective IgM deficiency’, ‘selective IgA deficiency’ or ‘common variable immunodeficiency’ will be included. For all patients, basic characteristics can be registered at first registration and yearly thereafter in level 1 forms. Detailed characteristics of the patients can be registered in level 2 forms. Consecutive follow-up forms can be added indefinitely. To ensure the quality of the collected data, all data will be fully monitored before they are exported from the ESID online Registry for analysis. Outcomes will be the clinical and immunological characteristics of unPAD at presentation and during follow-up. Subgroup analyses will be made based on demographical, clinical and immunological characteristics.

FEATURES OF DEVELOPMENT OF GENERALIZED PERIODONTITIS IN PERSONS WITH SECRETORY IMMUNOGLOBULIN A DEFICIENCY AND ITS TREATMENT (LITERATURE REVIEW)

OBJECTIVE

The aim: To present data on the possibility of occurrence and active progression of generalized periodontitis in persons with secretory immunoglobulin A deficiency and possible methods of its correction.

PATIENTS AND METHODS

Мaterials and methods: Analytical elaboration of scientific and medical literature based on the immunological aspect of generalized periodontitis.

CONCLUSION

Conclusions: The deficiency of secretory immunoglobulin A may occur in cases of primary or secondary insufficiency of the immune system. Selective IgA deficiency is an example of primary insufficiency of the immune system. Secondary immunodeficiency disorders is a clinical and immunological syndrome that develops against the background of a previously normally functioning immune system, characterized by a steady decrease in quantitative or functional indicators of specific or(and) nonspecific factors of immunoresistance. Insufficient awareness of dentists about certain aspects of the etiology and pathogenesis of generalized periodontitis leads to deterioration of treatment results.

Benign monoclonal gammapathy

The natural history of benign monoclonal gammapathy (BMG) has been followed by repeated studies of patients with M components through periods up to two decades. The disappearance of an M component is quite exceptional--in this material only once. Populations with increase in IgG, IgA and IgM have been studied separately. Slow, but steady, increase through many years may be found without development of myeloma (MM). Rapid transition from a steady state of the M component to progression is rare and usually, but not always, indicates the development of clearcut myeloma. Intermediate patterns are not uncommon and make it very difficult in rare individual cases to draw a sharp line between myeloma that should be treated and the benign state that should only be observed. The cause of pain may be difficult to judge. Osteolytic foci in the skull are usually diagnostic for MM, but vertebral fracture may also occur in osteopenia. It is evident that a period of at least three years of close observation without treatment should be the routine. "Prophylactic" treatment of BMG with cytostatic drugs should never be attempted.

Reversible hypogammaglobulinaemia

In this report we present four patients with reversible hypogammaglobulinaemia who required immunoglobulin substitution for several years. One patient had documented systemic lupus erythematosus (SLE), the other three patients had primary hypogammaglobulinaemia without known cause. Whereas the cessation of azathioprine therapy may have contributed to the recovery in the patient with SLE, the restoration of the immunoglobulin production in the other three patients occurred spontaneously. All four patients were IgA deficient when the hypogammaglobulinaemia was first detected and remained so after IgM and IgG production had recovered. Two of the three patients who also had anti-IgA antibodies started to produce anti-IgA again after stopping the immunoglobulin substitution. We conclude that recovery of hypogammaglobulinaemia is possible but rare. When recovery is suspected, we recommend that immunoglobulin substitution is stopped and the antibody response to vaccination is tested.

Kabuki syndrome with trichrome vitiligo, ectodermal defect and hypogammaglobulinemia A and G

We report a unique combination of symptoms in a case of Kabuki syndrome (KS), a multiple malformation/mental retardation syndrome that has a prevalence of 1:32,000 to 1:86,000. The patient was a mentally delayed 12-year-old male with trichrome vitiligo, ectodermal defect, and hypogammaglobulinemia A and G. This unique combination of signs, described here for the first time, indicates that KS comprises multiple deficits that affect not only the brain, but ectoderm-derived structures and the immune system as well. Our report may provide important clues for understanding the pathogenesis of the KS.

Measurement of immunoglobulin concentrations in the feces of healthy dogs

Selective immunoglobulin A (IgA) deficiency is the most common primary immunodeficiency in humans and may be associated with chronic gastrointestinal disease. This observation has led to the suggestion that the high susceptibility of German shepherd dogs (GSD) to chronic enteropathies is related to a deficiency in mucosal IgA production. Relative deficiencies of IgA has been reported in the serum, saliva, tears, and feces of GSD both with and without alimentary disease; however, the findings of different studies are not consistent. The aim of this study was to confirm whether a relative deficiency of IgA exists in the feces of GSD. Feces were collected from healthy GSD (n = 209), Labrador retrievers (n = 96), beagles (n = 19), and miniature schnauzers (n = 32). Fecal IgA, IgM, and IgG were measured by capture enzyme-linked immunosorbent assays. Fecal IgG concentrations in the four breed groups were not significantly different. IgA concentrations were significantly greater in miniature schnauzers than in GSD (P = 0.0003) and Labradors (P = 0.0004) but not significantly different from those in beagles. IgM concentrations were significantly greater in miniature schnauzers than in GSD (P < 0.0001), Labradors (P < 0.0001), and beagles (P = 0.0098). These findings do not support the hypothesis that GSD have a relative deficiency in fecal IgA. The differences in immunoglobulin concentrations measured from a single defecation, between individuals of the same breed and between breeds, as well as the lack of an internal control molecule, make the determination of a normal reference range for all dogs impossible. Therefore, the usefulness of fecal immunoglobulin quantification for the assessment of intestinal immunoglobulin secretion in dogs is limited.

[Secretory immunity of the airways]

INTRODUCTION

Continuous exposure of the respiratory tract to inhaled particles and microbes implies the presence of effective defence mechanisms at a bronchial and alveolar level.

STATE OF ART

Among the mechanisms involved secretory mucosal immunity contributes considerably to the defence of the bronchial tree. This immunity depends essentially on the active trans-epithelial transport of IgA involved in both innate non-specific and acquired specific immunity. Recently an IgA receptor has been identified on the surface of phagocytes including alveolar macrophages, establishing a link between alveolar and bronchial defences.

PERSPECTIVES

The respiratory mucosa represents a crucial interface between the host and its environment, and should provide in the future a new target for the development of diagnostic and therapeutic tools.

CONCLUSIONS

Beyond its function as an anatomical barrier the bronchial epithelium possesses a secretory activity that is essential for the protection of the lung. Despite a better understanding of mucosal immunity this secretory activity and in particular the part played by IgA remains to be elucidated.

Anaphylactic transfusion reactions

PURPOSE OF REVIEW

Although anaphylactic reactions to blood products are rare, the incidence of allergic reactions to blood products is similar to the allergic reaction incidence to penicillin antibiotics, and therefore worthy of proportionate attention. Comprehensive reviews and guidelines of the management of anaphylaxis currently do not include much information on blood products. Current guidelines for the specific management of anaphylactic transfusion reactions are contradictory as to the utility of anti-IgA testing and incomplete by not offering suggestions for the management of non-IgA related reactions.

RECENT FINDINGS

Anti-IgA is not responsible for most reactions. Anti-haptoglobin antibodies are responsible for more reactions than anti-IgA in Japan, but the cause of most reactions is still not known. The incidence of reactions to platelets is the highest compared with fresh frozen plasma and red blood cells. Pre-storage white blood cell reduction of platelets does not decrease the incidence of reactions, indicating that white blood cell-derived cytokines are not responsible for most reactions.

SUMMARY

The increased incidence of reactions to platelets compared with fresh frozen plasma suggests that a platelet-related factor may be responsible for many of the reactions. The possible role of platelet microparticles or activated platelet membranes, which carry a negative charge similar to ionic radiocontrast media, the major cause of iatrogenic anaphylactic reactions in the hospital, is explored.

Antibody and genetic testing in coeliac disease

The description of a range of antibodies associated with coeliac disease has been an important development in the ability to test for this common and treatable condition non-invasively. However, the detection of these antibodies remains unstandardised and the appreciation of the clinical utility of each is evolving. In view of the advances in the diagnosis and understanding of coeliac disease, we discuss: (1) the relative advantages, disadvantages and comparative diagnostic utility of the different antibody tests including the confounding effect of selective IgA deficiency; (2) various technical aspects of these tests; (3) HLA-DQ typing as a supplementary tool to antibody testing; (4) areas of controversy resulting from insufficient or conflicting published data; and (5) potential testing strategies.

Neutropenia associated with primary immunodeficiency syndromes

The primary immunodeficiency diseases are a heterogeneous group of more than 75 disorders characterized by intrinsic defects in the functions of the immune system. Many are associated with abnormalities of hematopoiesis as well. This article will review those primary immunodeficiency syndromes in which neutropenia is a prominent finding, including X-linked agammaglobulinemia (XLA), hyper IgM syndrome, common variable immunodeficiency (CVID), IgA deficiency, cartilage-hair hypoplasia (CHH), and reticular dysgenesis, with regards to pathophysiologic findings and treatment.

Spontaneous resolution of profound hypogammaglobulinemia

A 3-month-old, full-term female infant was hospitalized with pneumonia and bronchiolitis. Laboratory studies revealed a profoundly low level of IgG (41 mg/dL) and low level of IgA (< 6.67 mg/dL). Other causes of immunodeficiency were ruled out, and there was no evidence of protein loss to account for the low immunoglobulin levels. The immunoglobulin levels normalized over time. Our patient had a transient hypogammaglobulinemia of infancy, with severely low IgG and low IgA levels. We found no other reports of cases with such low values of IgG that proved to be transient.

Reliance on serum endomysial antibody testing underestimates the true prevalence of coeliac disease by one fifth

BACKGROUND

Although IgA endomysial antibody (EmA) is currently the serologic test of choice in selecting suspected coeliac patients for duodenal biopsies, false-negative cases have been reported and may be more common than previous studies suggest. We assessed the sensitivity of EmA for patients with biopsy-confirmed villous atrophy (VA).

METHODS

We studied 89 patients without IgA deficiency for whom biopsy had not been primarily prompted by a positive EmA result. VA was graded as partial, subtotal, or total (PVA, STVA, TVA). Serum EmA was assayed with indirect immunofluorescence.

RESULTS

The sensitivity of EmA for VA was 78% (69 of 89) and was similar for PVA (79%) and ST/TVA (77%). Only 4 of the 20 EmA-negative patients had increased serum IgA-class antigliadin antibody levels as measured with enzyme-linked immunosorbent assay. All seronegative patients who complied with dietary gluten exclusion responded clinically, with histologic improvement after 12 months in 8 (67%) of 12 patients who had follow-up biopsies.

CONCLUSIONS

EmA-negative coeliac disease is common. Reliance on EmA testing to select patients for biopsy will result in significant underdiagnosis.

The transfusion needs of an autologous bone marrow transplant patient with IgA deficiency

BACKGROUND

Transfusion management of the patient who is undergoing a marrow or peripheral blood stem and progenitor cell transplantation is often challenging. The situation is further complicated when the patient is IgA deficient with circulating anti-IgA.

CASE REPORT

This report describes an approach to transfusion therapy primarily using red cells washed by automated techniques and cryopreserved autologous plateletpheresis components. Additional platelet support was provided with manually washed allogeneic plateletpheresis components. Autologous fresh-frozen plasma was collected concurrently, and IgA-deficient allogeneic units were ordered and kept in storage, but they were not needed during transplantation. The patient experienced no transfusion sequelae as a result of the IgA deficiency.

CONCLUSION

With this approach, the transfusion needs of an IgA-deficient patient were adequately met during bone marrow transplantation.

Role of immunoglobulin subclasses and specific antibody determinations in the evaluation of recurrent infection in children

We studied humoral immune function in 267 children with recurrent respiratory infections referred to our immunology clinic to determine the most appropriate immunologic studies for evaluating recurrent infections in children. Of this highly selected population, 58% had a partial deficiency in one or more of the major immunoglobulin isotypes or IgG subclasses (defined as at least 2 SD below the normal age-adjusted mean). In none of the patients was there a total absence of an immunoglobulin isotype. The most common abnormality was partial IgA deficiency, which was found in one third of the patients. Twenty-six patients had only partial IgG subclass deficiencies, of which 20 were deficiencies of a single subclass. IgG1 was an isolated partial defect in three patients, IgG3 in five patients, and IgG2 and IgG4 were selective partial defects in six patients each. Tetanus toxoid and pneumopolysaccharide type 3 were the most immunogenic of the immunogens tested; hyporesponsiveness to pneumococcal polysaccharide types 7, 9, and 14 was common. Nineteen percent of the patients with normal immunoglobulin concentrations who were tested had lower-than-expected antibody titers; 42% of those tested with partial isotype deficiencies had deficient antibody responses. Of 25 patients with selective partial IgG subclass deficiencies or combined IgG subclass deficiencies, eight had antibody deficiencies. Our findings indicate that a high proportion of children referred to immunology clinics for recurrent infection have a demonstrable immunologic abnormality. Selective IgG subclass deficiency or a combined IgG subclass deficiency without an associated deficiency in a major immunoglobulin isotype is unusual. Identification of such patients is not predictive of the capacity to form antibodies to the antigens tested in this study and, in our opinion, adds little to the initial evaluation of immune function in such children.

The role of the immunologist in sinus disease

The clinical immunologist is playing an increasingly important role in the evaluation and management of sinus disease. Although most patients with sinus disease are not immunodeficient, a significant proportion of patients with chronic sinusitis unresponsive to medical and/or surgical therapy may have an immunodeficiency. Most immunodeficient patients for whom sinusitis is a major clinical problem tend to be those with humoral immunodeficiency diseases. The role of immunoglobulin replacement therapy is well established for patients with global immunoglobulin and antibody deficiencies (e.g., X-linked agammaglobulinemia and common variable immunodeficiency) and may be helpful in controlling refractory sinusitis in patients with more selective immunoglobulin deficiencies (e.g., IgG subclass deficiency and selective antibody deficiencies), but efficacy in these conditions remains to be established by controlled studies. Many immunodeficient patients have a history of repeated sinus surgery before the recognition of their immune defect. Even in immunodeficient patients treated with antibiotics and immunoglobulin replacement therapy, functional endoscopic sinus surgery is successful in only half of the patients.

Involvement of both HLA and Ig heavy chain haplotypes in human IgA deficiency

Immunoglobulin-A deficiency (IgA-D) is the most common human Ig class deficiency with an estimated frequency of approximately 1 in 500 in the Swedish population. We investigated the immunoglobulin heavy chain constant region gene segments (IGHC) in 103 individuals with IgA-D and the immunoglobulin heavy chain variable region gene segments (IGHV) in 20 of these, in order to identify a possible molecular basis of the defect. No deletions of IGHV gene segments of the VH2, VH5, and VH6 families or the IGHG genes were observed. In the IGHC, there were, however, differences in the restriction fragment length polymorphism frequencies of IGHG genes where the Bam HI haplotype "H2" [IGHGP, 10 kilobases (kb), IGHG2, 25 kb; and IGHG4, 9.0 kb] was overrepresented. The mean serum levels of IgG4 and IgE were significantly lower in individuals (both IgA-D subjects and healthy controls) homozygous for the H2 haplotype than in individuals homozygous for the H1 haplotype (IGHGP, 8.8 kb, IGHG2, 13.5 kb, and IGHG4, 9.4 kb). IgA-D subjects homozygous for HLA DQB1*0201 (DQw2), a marker that has previously been reported to show a strong association with IgA deficiency, showed a similar reduction of serum levels of IgG4 and IgE as compared with DQB1*0201 negative IgA-D subjects. These findings suggest that the two loci found to be associated with IgA deficiency may act via a common pathway.

The association of IgA deficiency but not IgG or IgM deficiency with a reduced patient and graft survival following liver transplantation

Recipients of solid organ allografts require lifelong immunosuppression in order to prevent graft rejection and to maintain graft function. In general, such immunosuppression greatly impairs the cellular immune system, as this level of the immune system is principally responsible for self and non-self recognition. The consequences of allograft transplantation in terms of patient and graft survival when transplants are given to individuals who have a preexisting humoral immune deficiency characterized by a deficiency of the serum levels of one or more of the major Ig classes have not yet been reported. From February 1, 1981 through December 31, 1990, a total of 43 adult patients with a deficiency of 1 or more Ig classes received a ABO-matched liver allograft at this institution. This sample represents 2.5% of a total of 1684 adults transplanted during this interval. These 43 liver graft recipients could be divided into 3 major groups based upon the presence of an IgG, IgM, or IgA deficiency. IgG deficiencies were defined as levels less than 50 mg/dl. Patient and graft survival for the IgA-deficient group was significantly reduced (P less than 0.04 and P less than 0.009, respectively) compared with both the IgG- and IgM-deficient groups. The latter two groups did not differ from controls without an Ig deficiency for these same two endpoints. The major causes of death in the IgA-deficient group were sepsis and opportunistic infection. A third of the deaths in the IgA-deficient group occurred in the perioperative period (first 30 days) while greater than 50% of the deaths occurred within the first 3 months, and all deaths occurred before the first year. Based upon these data, the following conclusions can be made: (1) serum IgA deficiency but not IgG or IgM deficiency is associated with an increased post-OLTx death and graft loss rate; (2) the majority of these deaths are due to sepsis or an opportunistic infection; and (3) most of the deaths occur early. These data suggest that recognition of a deficiency of IgA prior to organ grafting necessitates meticulous attention to the prevention of infection in the immediate perioperative period if patient and graft survival of these patients is to be improved.

Aberrations in titre and avidity of serum IgM and IgG antibodies to microbial and food antigens in IgA deficiency

The antibody levels and relative avidity of serum IgM and IgG antibodies against E. coli O antigens, poliovirus type 1 and beta-lactoglobulin were determined with enzyme-linked immunosorbent techniques in IgA deficient (IgAd) patients with frequent respiratory tract infections and healthy IgAd individuals. Healthy individuals with normal immunoglobulin levels served as controls. The IgM antibody levels against the bacterial, viral and food antigens and the IgG antibody levels against the bacterial antigens were significantly higher in the IgAd group with recurrent infections than in the group of healthy IgAd individuals. The symptomatic IgAd group had significantly higher levels of the IgG antibodies against the bacterial antigen, also when compared with controls. In contrast the healthy IgAd individuals had the highest avidities of IgM antibodies to the viral and food antigens. The high avidities of antibodies could be a compensatory host defence mechanism in IgAd. These aberrations may appear as a consequence of increased mucosal exposure in IgAd to antigens such as E. coli or beta-lactoglobulin, but presumably not to poliovirus which is only exceptionally present in the milieux. They could also be a result of the previously suggested dysregulation of antibody responses in IgAd.

Presence of non-maternal antibodies in newborns of mothers with antibody deficiencies

To explain the mechanism for induction and production of specific antibodies found in the newborn already at birth, without previous known exposure to the antigen, we chose a model that presumably excluded the possibility of specific antibodies being transferred from the mother to the fetus. Specific IgG, IgA, and IgM antibodies against Escherichia coli and poliovirus antigens were determined with ELISA in serum, saliva, and amniotic fluid from hypogammaglobulinemic and IgA-deficient mothers as well as in cord serum, saliva, and meconium from their offspring. All the mothers lacked IgA and some also lacked IgM antibodies, which were found in their healthy newborns. The amniotic fluid from a hypogammaglobulinemic mother lacking IgA contained small amounts of IgA antibodies, which were also found in the neonate, suggesting a fetal origin. There was evidence for the presence of antiidiotypic antibodies to poliovirus in the cord sera. We propose that idiotypic and/or antiidiotypic IgG antibodies transferred via the placenta from the mother to the fetus can initiate specific immune responses seen in the newborn. Thus, it may be that transplacental IgG not only passively protects the newborn, but also actively primes the fetus during fetal life via its content of idiotypic and/or antiidiotypic antibodies.

The prevalence of selective IgA deficiency in type 1 diabetes mellitus

A significant increase in the prevalence of selective IgA deficiency has been observed in patients with autoimmune disorders such as systemic lupus erythematosus and rheumatoid arthritis. Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease and susceptibility to both IDDM and IgA deficiency is associated with HLA DQB1 alleles encoding non-Asp amino acids at position 57. In order to assess whether the prevalence of selective IgA deficiency is increased in IDDM, we have screened a homogeneous series of adult patients with IDDM for selective IgA deficiency. One patient (1:261) was found to have a selective IgA deficiency. The prevalence of selective IgA deficiency among adult French blood donors is 1:1400. Thus, although IDDM and selective IgA deficiency are both associated with the presence of non-Asp amino acids at position 57 of the HLA DQ beta chain, the frequency of this immunodeficiency in adult IDDM patients is not significantly increased.

Major histocompatibility complex class III genes and susceptibility to immunoglobulin A deficiency and common variable immunodeficiency

We have proposed that significant subsets of individuals with IgA deficiency (IgA-D) and common variable immunodeficiency (CVID) may represent polar ends of a clinical spectrum reflecting a single underlying genetic defect. This proposal was supported by our finding that individuals with these immunodeficiencies have in common a high incidence of C4A gene deletions and C2 rare gene alleles. Here we present our analysis of the MHC haplotypes of 12 IgA-D and 19 CVID individuals from 21 families and of 79 of their immediate relatives. MHC haplotypes were defined by analyzing polymorphic markers for 11 genes or their products between the HLA-DQB1 and the HLA-A genes. Five of the families investigated contained more than one immunodeficient individual and all of these included both IgA-D and CVID members. Analysis of the data indicated that a small number of MHC haplotypes were shared by the majority of immunodeficient individuals. At least one of two of these haplotypes was present in 24 of the 31 (77%) immunodeficient individuals. No differences in the distribution of these haplotypes were observed between IgA-D and CVID individuals. Detailed analysis of these haplotypes suggests that a susceptibility gene or genes for both immunodeficiencies are located within the class III region of the MHC, possibly between the C4B and C2 genes.

Unusual selective immunoglobulin deficiency in an Arabian foal

A 10-month-old Arabian foal was evaluated for a suspected immunoglobulin (Ig) M deficiency. Decreased to nondetectable concentrations of IgM, IgA, and IgG (T), and a normal concentration of IgG, were present. Results of in vitro testing of the blood lymphocyte blastogenesis showed a weak response to the B-cell mitogen, lipopolysaccharide (LPS), but normal responses to T-cell mitogens. Results of postmortem examination showed synovitis of the left tibiotarsal and both scapulohumeral joints. Atrophy and edema of the lymph nodes and lymphocyte depletion in the thymus and spleen were seen. A subacute inflammatory infiltrate was observed in the kidney, synovium, liver, and brain. Etiologic agents were not identified. This case represents a previously unreported form of immunodeficiency disease in the horse.

[Lymphoid hyperplasia of the intestine in children. 15 cases]

Fifteen cases of nodular lymphoid hyperplasia (NLH) of the bowel in patients aged 17 months to 15 years are reported. Fourteen patients had NLH confined to the small bowel and one had involvement of both the small bowel and colon. Mean age at diagnosis was 10 years. The most common presenting symptoms were intestinal manifestations (86%). Diagnosis was suspected upon roentgenographic studies in one case and digestive endoscopy in ten cases. Histologic confirmation was obtained in all fifteen patients. Immunohistochemical studies, done in 8 patients, demonstrated a paucity of IgA plasmocytes in one patient with an immune deficiency and a polyclonal plasmocyte population with mainly IgA plasmocytes in the seven other patients. Five patients had a deficiency in humoral immunity, with variable expression hypogammaglobulinemia in three patients and IgA deficiency in two; intestinal giardiasis was found in eight patients. Histologic outcome was documented in five cases; evidence of NLH disappeared in only one patient. Metronidazole improved clinical symptoms in most instances.

Immunoglobulin levels during follow-up of children with selective IgA deficiency

Longitudinal serum immunoglobulin levels were studied in 36 children with selective IgA deficiency during a median follow-up period of 5 years. Twenty-five children were 'sporadic' cases, and 11 were 'familial'. Serum and saliva IgA levels in 23 children remained below 2 mg/l. Eight children with IgA levels above 2 mg/l showed considerable intra-individual variance in serum IgA, but remained IgA deficient. Five children at various ages developed IgA levels above 50 mg/l with detectable secretory IgA in saliva. In most of the children IgG subclass levels were found to be rather high, including at younger ages. There were no obvious differences between 'sporadic' and 'familial' cases except an association between IgD deficiency and serum IgA levels below 2 mg/l, and between serum levels of IgD above 1 IU/ml and of IgA above 2 mg/l, which was found to be significant in the 'sporadic' group but not in the 'familial' group.

Immunogenicity of Haemophilus influenzae type b capsular polysaccharide and its tetanus toxoid conjugate in patients with recurrent infections or humoral immunodeficiency

The antibody response to the capsular polysaccharide of Haemophilus influenzae type b was evaluated after vaccination with the capsular polysaccharide or its tetanus toxoid conjugate in 41 randomized patients with recurrent infections, IgA deficiency, common variable immunodeficiency, or the Wiskott-Aldrich syndrome. Serum antibodies were measured using a Farr assay for total antibodies and an enzyme-linked immunosorbent assay for antibodies of the three main immunoglobulin classes and of each IgG subclass. Antibody levels reached concentrations generally considered as protective in the majority of cases, the best response being observed after two injections of the conjugate vaccine with a 1-month interval. Vaccination with the conjugate therefore seems to be promising for the prevention of Haemophilus influenzae type b infections in such patients.

Selective IgA deficiency and coeliac disease

Twenty-five children and adults with concomitant coeliac disease and selective IgA deficiency are described. IgG-class reticulin antibodies were positive in 94%. The clinical course of coeliac disease did not differ from that of patients with normal serum IgA level. Patients with IgA deficiency also had other concomitant diseases, especially autoimmune diseases. Patients with selective IgA deficiency have at least a tenfold risk of coeliac disease compared with the population in general.

Abnormalities in immune regulation precede the development of multiple myeloma

Immunosuppression of immunoglobulin synthesis seen in patients with multiple myeloma is in part due to immunosuppressive CD5 positive B cells. In a 13 year longitudinal study of an IgA-deficient blood donor who developed multiple myeloma, the presence of immunosuppressive CD5 positive B cells and T cells preceded the diagnosis of overt multiple myeloma and the appearance of immunosuppressive monocytes. These data argue that certain immune defects may be involved in the development of myeloma and are not simply a consequence of overt malignancy.

[IgA deficiency: clinical ans immunological evaluation of 28 patients]

Seventeen patients with total IgA deficiency and II with partial IgA deficiency were investigated. Symptoms associated with IgA deficiency were retrospectively studied, and the levels of other immunoglobulins were measured in blood and in saliva. The most important associated complaints were recurrent upper respiratory infections. More than 50% of the symptomatic patients recovered clinically, associated with a recovery of the IgA level or with compensatory humoral immunological mechanisms (such as elevated IgG subclasses or strongly positive secretory IgM). The necessary diagnostic procedures, follow-up of patients and families are described.

IgG subclass deficiency in children with recurrent bronchitis

We studied the incidence of IgG subclass deficiency in children with recurrent bronchitis. Recurrent bronchitis was defined as three or more episodes a year during at least 2 consecutive years, of bronchopulmonary infection, productive cough with or without fever and/or diffuse râles by physical examination in the absence of asthma or atopy. Fifty three children were selected, of whom 30 (57%) were deficient in one of the IgG subclasses. None had an IgG1 deficiency. Nine (17%) were deficient in IgG2, 9 (17%) in IgG3 and 20 (38%) in IgG4. Isolated IgG subclass deficiencies were most frequently seen for IgG4 (14, 26%), less for IgG3 (6, 12%) and even less for IgG2 (4, 7%). Nine (17%) children were IgA deficient and 8 (15%) IgG deficient with a combined IgG subclass deficiency in 8 and 7 of them respectively. By subdivision into different age groups most patients were encountered in the youngest group. The mean content of IgG2, IgG3 and IgG4 in 3- to 4-year-old children with recurrent bronchitis was significantly lower than in the age matched controls. The mean value for IgG4 in the 5- to 6-year-olds was significantly lower than in the control group. This study demonstrates the correlation between recurrent bronchitis in childhood and IgG subclass deficiency. IgG subclass deficiency and recurrent bronchitis are both quite prominent phenomena in young children but rare in older children, suggesting a transient immaturity of the immune system as one of the possible pathogenetic factors. An IgA or an IgG deficiency is highly suggestive for the existence of a combined IgG subclass deficiency.