We studied the relationship of serum levels of IgA and IgE to allergic manifestations and otitis media in a cohort of 179 icelandic children, aged 18 to 23 months. Only one of the infants had IgA deficiency (<50 μg/ml); all the others had IgA levels that were normal for their age. The children were divided into three groups according to their IgA levels (lowest 25%, intermediate 50%, highest 25%) and the clinical findings analyzed accordingly. The cumulative incidence of definite allergic manifestations was 37%. Asthma and otitis media were significantly more common among the infants with low normal IgA levels than among those with intermediate to high IgA levels. There was also a significant association between the severity of allergic manifestations and low IgA levels (p=0.002). Children with detectable IgE (≥0.23 kilounit/L) had a higher incidence of atopic manifestations than did children in whom IgE was not detectable, but only a weak correlation was found between the occurrence and extent of allergic symptoms and increasing amounts of IgE beyond the 0.23 kilounit/L level. These findings suggest that atopic manifestations in infants may be more dependent on delayed maturation of IgA production than on overproduction of IgE.
Atopic diseases are polygenic and have a complex etiologic picture; their pathogenic mechanisms involve regulatory T lymphocytes.1, 2 Although IgE antibodies play a central role in mast-cell-mediated allergic reactions, a protective function of IgA is suggested by the increased incidence of atopic manifestations in children with IgA deficiency. 3 It has also been argued that transient IgA deficiency caused by delayed maturation of IgA production may predispose children to atopic manifestations. 4-6 Deficiency of IgA is also associated with an increased incidence of upper respiratory tract infections. However, manifestations of allergy or infections have, to our knowledge, not been analyzed in the context of Supported by the Icelandic Ministry of Health and the Science Council of Iceland. Submitted for publication June 13, 1991; accepted Jan. 14, 1992. Reprint requests: H. Valdimarsson, MD, Department of Immunology, Landspitalinn, 101 Reykjavlk, Iceland. 9/20/36395 different IgA levels within the normal range (log mean + 2 SD). This study was originally designed to determine the optimal level of cord blood IgE that might be used to select newborn infants for an allergy prevention program\] A total of 179 infants with either high levels of IgE or no detectable IgE at birth were therefore examined clinically when they were 18 to 23 months of age. However, we failed to demonstrate any correlation between cord blood IgE levels and atopic disorders (unpublished observations). This