Effect of thymic humoral factor on cellular immune factors of normal children and of pediatric patients with ataxia telangiectasia and Down's syndrome.

Cellular immune functions of nine Down's syndrome patients and of nine was Ataxia telangiectasia vs. nine normal children and nine cord bloods, were evaluated using in vitro assays of peripheral blood lymphocytes. The in vitro assays included E rosette formation, antilymphocytic cytotoxicity by an antithymic antiserum and leukocyte migration inhibition factor (LIF) production. The mitogens and antigens used were phytohemagglutinin, purified protein derivative, and monilia antigen. The effect of a thymic hormone (THF) on these parameters was evaluated and it was administered therapeutically to three Down's syndrome patients and to two patients with Ataxia telangiectasia. Most deficient T-cell functions were reversed to normal after incubation of the lymphocytes with THF, or after THF therapeutic administration. In two Down's syndrome cases, the clinical course was not altered by THF administration, while one seemed to benefit from it markedly. One of the Atactic patients recovered from a severe viral infection, while the other died from intractable bronchopneumonia.