Clinical phenotype classification for selective immunoglobulin A deficiency.

Selective immunoglobulin A deficiency (SIgAD) is the most common predominantly antibody deficiency, with a wide range of presentations from asymptomatic to severe manifestations. Although many studies have investigated different aspects of SIgAD, no study has yet presented a comprehensive classification of this disease. Based on clinical manifestation of patients and various immune abnormalities associated with SIgAD, this group of patients could be classified into five different phenotypes including asymptomatic, minor infectious, allergic, autoimmune and severe phenotypes. This classification aids physicians in identifying patients and in choosing appropriate management and treatment as well as homogenized groups for molecular and genetic studies.

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

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

IgA deficiency: correlation between clinical and immunological phenotypes.

BACKGROUND: IgA deficiency (IGAD) is the most common primary antibody deficiency. Although many affected individuals have no apparent symptom, selected patients suffer from recurrent mucosal infections, allergies, and autoimmune diseases. We aimed to investigate the clinical features in relation to immune function of Iranian patients with symptomatic IGAD. METHODS: Thirty-seven patients (21 male and 16 female), aged 4-32 years, were evaluated in this study. Patients were followed for a total of 131 patient years with a mean follow-up of 3.5 years per patient. RESULTS: The most prevalent presentations were recurrent infections occurring in 27 subjects, followed by allergy in eight cases and autoimmunity in two patients. However, during the follow-up period, 35 patients developed infections in respiratory and gastrointestinal tracts, necessitating medical care. Apart from infections, allergy was the most frequent complaint (31 cases); the major features were asthma, atopic dermatitis, and allergic rhinoconjunctivitis. Autoimmune diseases were documented in ten cases; thyroiditis was the most common. In 31 patients who received unconjugated pneumococcal polyvalent vaccine, antibody response against polysaccharide antigen was measured before and 28 days after vaccination. One fourth of vaccinated patients were hyporesponsive to vaccine; four of these patients developed bronchiectasis. The patients with IGAD were classified into two groups: group 1 (14 cases) consisted of patients with IGAD and other associated immune defects, such as immunoglobulin G (IgG) subclass deficiency and defective specific antibody production. Group 2 (23 cases) had isolated IGAD without other immunological abnormalities. There was a significantly increased number of lower respiratory tract infections in group 1 compared with group 2 (P = 0.006). Moreover, four patients of group 1 had bronchiectasis whereas none of the patients in group 2 developed this complication (P = 0.015). CONCLUSION: Subclassification of IGAD regarding the existence of associated immune defects is useful in terms of morbidity and planning for medical care. IgA-deficient patients with concomitant immune defects such as defects in specific antibody production have higher rates of recurrent infections and bronchiectasis, which necessitates more effective monitoring.

Deficiencia de IgA / IgA deficiency

El déficit selectivo de IgA es la forma más leve de inmunodeficiencia primaria. En la mayoría de estos niños, si no hay una enfermedad asociada, el pronóstico es excelente. Muchos de los deficientes, diagnosticados o no, continuarán su vida sin ningún tipo de problema. Sin embargo otros tienen abundantes problemas porque la deficiencia aislada de IgA puede asociarse con enfermedades como alergia, enfermedades con base autoinmune (enfermedad celíaca, hipotiroidismo, colagenosis, etc.). Por tanto, en la deficiencia de IgA que se asocia a otras enfermedades, el pronóstico lo marca la enfermedad a la que se asocia. Algunos niños con deficiencia selectiva de IgA presentan recuperaciones espontáneas. Estos niños son subsidiarios de seguimiento para la detección temprana de los trastornos y las complicaciones concomitantes (AU)

Evaluation of the relevance of humoral immunodeficiencies in a pediatric population affected by recurrent infections.

Recurrent infections are a common cause of morbidity in childhood. Several reports have associated this condition to low levels of IgA and IgG subclasses and/or lack of specific antipolysaccharide antibody response, although the relevance of these defects in terms of prognosis and therapeutic approach is still unclear. The aim of our study was to determine the frequency and the clinical relevance of humoral immunodeficiency (HID) other than hypogammaglobulinemia in children affected by recurrent infections. We recruited 67 pediatric patients affected by recurrent infections. Serum IgG, IgA, IgM, IgG2, IgG3, and specific anti-Haemophilus influenzae (anti-Hib) antibodies were determined. Thirty-seven out of 67 patients showed antibody defects (55%). IgA deficiency was observed in 21 out of 67 patients (31%), followed by IgG2 (18%), IgG3 (15%) and IgM (6%) defects. Anti-Hib deficiency was present in three out of 44 patients (7%). A tendency for a higher occurrence of pneumonia and otitis, although not statistically significant (p > 0.05), was observed in HID patients compared to children with normal humoral function. No statistical difference as to the frequency of mild infections (URI) was found between HID and non-HID patients. We therefore suggest that the therapeutic program is based on the clinical status of the patients. Long-term follow-up with repeated determinations of antibody levels is crucial, however, to detect those defects that might evolve into more complex immunodeficiencies.