Correlation between serum immunoglobulin A concentrations and allergic manifestations in infants.

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 (less than 50 micrograms/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 (greater than or equal to 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.

Antibody production in the brain tissue of mice immunized into the central nervous system.

Injection of T-dependent antigens into the subarachnoid space and brain parenchyma induced a marked antibody production in the spleen, as detected by plaque-forming cells (PFC). The presence of specific antibody-producing cells in the brain tissue was only observed in those animals which received antigenic challenge into the central nervous system. Local antibody production requires successive antigenic challenges with doses of sheep red blood cells larger than 2 X 10(4). Brain trauma did not influence the background numbers of spleen PFC nor did it induce the appearance of antibody-producing cells in the brains of mice challenged intra-peritoneally. The presence of specific antibody-producing cells in the brain tissue following antigenic challenge within the CNS suggests that a local immune response can be maintained in this organ.