Improvement of cellular immunity and IgA production in immunodeficient children after treatment with synthetic serum thymic factor (FTS).

Three children with IgA and IgE deficiency and T-cell defects (two related patients with ataxia telangiectasia and one with common variable immune deficiency) were treated with synthetic serum thymic factor (FTS) intravenously. A reduction in frequency and severity of infection was noted concomitantly with improvement in cell-mediated-immunity tests. Serum IgA, which was absent in two patients, appeared within 4 weeks of treatment and increased significantly in the third patient. Specific antibodies against vaccination antigens appeared for the first time or increased to titres higher than ever before. In two patients, transient interruption of FTS administration was followed by a regression of the immunological improvement, but this disappeared after the treatment was started again.