Lack of Association between IgA Deficiency and Respiratory Atopy in Young Male Adults

Background: The issue of atopy and increased serum IgE in IgA deficiency is still a matter of debate. The aim of this study was to evaluate the prevalence of IgA deficiency and its relationship with respiratory atopy. Materials and Methods: A retrospective study on 4700 consecutive young males (age range 18-23), who underwent a health screen for admission to the Italian Airforce Academy between 1993 and 1995 was conducted. Serum IgA was measured by immunoturbidimetry and total and specific IgE by fluorescent enzyme immunoassay (Phadiatop FEIA, Pharmacia Cap System). Airway responsiveness was assessed by methacholine challenge. Results: IgA deficiency was detected in 0.34% (16/4700) subjects and atopy was detected in 8.6% (406/4700). The mean IgA was 243 mg/dl (95% CI 107, 442) in the 406 atopic subjects and 238 mg/dl (95% CI 100, 441) in 1544 controls. Only 6 (37.5%) of the IgA deficient subjects had subnormal IgE levels and 6 were positive in the fluorescent EIA. None of the IgA deficient patients presented with respiratory hyper-reactivity. Conclusion: Atopy is not more prevalent in young male adult IgA deficient subjects, who rather display a high frequency of recurrent sinusitis. Selective IgA deficiency is the most common inherited immunoglobulin disorder characterized by serum IgA levels <5 mg/dl in the presence of normal or increased serum levels of IgG, IgM or IgE. Its prevalence ranges from 1:300 to 1:3000 according to the population under study (1). A figure of 0.35% was derived from apparently healthy young Italian male adults (2, 3) though it may be present in 2.66% of Caucasians. The clinical significance of IgA deficiency is unclear (4) since it has been detected in healthy people as well as in patients with autoimmune (5) and atopic disorders (6, 7). The lack of IgA in serum is often associated with a reduced level of secretory IgA (8), but this does not seem to predispose to an increased frequency of infections unless a concomitant deficiency of IgG subclasses (particularly IgG2) is present. In this case infections may be more frequent and clinically more relevant (9, 10). Many studies have investigated the possible role of IgA deficiency and the development of allergic symptoms (11-13). To date the results are still very controversial. A possible role of IgA deficiency on the emergence of airway hyperresponsiveness (AHR) has also been suggested (14). The prevalence of IgA deficiency and its association with atopy and bronchial responsiveness was retrospectively evaluated in a large population of young male candidates to the Italian Air Force Academy between 1993 and 1995.