Immunological investigations in two brothers with ataxia telangiectasia Louis-Bar.

Two of three brothers with the classical signs of ataxia telangiectasia were investigated for their immunological disorders at the ages of 13 and 16 years, respectively. The elder brother also suffers from autoimmune hemolytic anemia, a complication which has not yet been described in the course of ataxia telangiectasia. Immunological investigations made in both brothers showed a reduction in the number and function of T lymphocytes. The number of B lymphocytes was normal, among which there were cells staining for IgA, although serum IgA was absent. It seems possible that this phenomenon is caused by a disturbance in the process of maturation of lymphoid cells with a lack of differentiation into IgA-synthesizing plasma cells.