Immunologic Aspects of Ataxia-Telangiectasia

Abstract

Two siblings with typical ataxia-telangiectasia (A-T) had opposite immunoglobulin patterns. One, a boy, had pan-hypogammaglobulinaemia, depressed delayed hypersensitivity and prolonged rejection time of skin homografts. His sister had increased levels of Ig [immunoglobulin]G and IgM-globulin but decreased levels of IgA-globulin. She also had depressed delayed hypersensitivity and prolonged rejection time of skin homografts. Low agglutinin and antitoxin titers in both further indicate immunologic incompetence. The thymus shadow in both children was abnormal, suggesting an aplastic thymus in 1 and a hypoplastic in the other-when visualized by pneumomediastinography and stratigraphy. Both children had high leukocyte levels of alkaline phosphatase. This was a feature of Down''s syndrome, and the probands'' brother with Down''s syndrome died of bronchopneumonia. Some of the genetic problems of ataxia-telangiectasia, and the relationship of this syndrome to the Swiss-type of aggamaglobulinemia and to the so-called acquired form of immunological deficiency are discussed. The role of the thymus in the promotion and maturation of the immunological system is considered.