Abnormal OKT4/OKT8 ratio and deranged capping in ataxia-telangiectasia.

Two sisters with ataxia-telangiectasia (A-T) and their parents were investigated for some parameters related to immunological functions. We found a decrease of total mature T lymphocytes, a decrease of OKT4+ helper-inducer T subset, and normal values of OKT8+ suppressor-cytotoxic T subset; a normal decrease of E rosette formation after incubation in vitro with theophylline, with a lowered E rosette capacity in one patient. The responses to phytohemagglutinin (PHA)and concanavalin A (ConA) were lowered. In addition we observed a reduction of basal capping of B lymphocytes in one patient and in her parents: this phenomenon could be related to cytoskeletal disorders, possibly involved in the pathogenesis of the disease.