Serum IgE levels in patients with selective IgA deficiency.

In this study serum IgE levels were measured by a double-antibody radioimmunoassay in 31 patients with serum IgA concentration less than 0.01 mg/ml who were followed in the arthritis and allergy clinics. On a group basis there was no significant difference in mean serum IgE levels between the IgA deficient patients and normal subjects of the same age. However, in the absence of atopic disease, IgA deficient patients had significantly lower serum IgE levels. When atopy was associated with IgA deficiency IgE levels were the same as in the normal subjects but significantly lower than those of atopic non-IgA deficient patients. IgE levels in those with recurrent respiratory tract infection were not different. Adults with anti-IgA antibodies had significantly lower IgE values. IgE levels in patients with RA, JRA or SLE were not significantly different. Selective IgA deficient patients may have a relative deficiency of serum IgE depending on the comparison group.