Clinical and immunological features of transient IgA deficiency in children.

Of eighteen children, in whom no IgA was detected in serum or whole saliva, twelve remained IgA-deficient, but six developed normal IgA levels between the age of 5 and 13 years. In the former, allergic asthma, elevated serum IgM and IgE levels, a high number of IgE-bearing and -containing peripheral lymphocytes, and rather low numbers of circulating T cells and PHA responses were common. Conversely, most of the latter suffered from respiratory tract infections, had normal T and B cell assays, serum IgM and IgE and no asthma. When serum and saliva IgA increased, their recurrent respiratory tract infections ceased.