Development of a serologically complete IgA deficiency in a patient with common variable hypogammaglobulinemia

A male with common variable hypogammaglobulinemia had subnormal but detectable IgA levels (0.2-0.4 g/l). During a period of 1 yr his serum IgA decreased below the detection level to less than 1/10(5) of the original concentration. Serum IgG and IgM were both low but remained constant during the follow-up time. In serum samples lacking IgA, anti-IgA antibodies of the IgG1 subclass were found. His B lymphocytes had a low but detectable capacity to secrete IgA in coculture experiments with purified T cells from healthy donors.