Impaired cellular interactions involving lymphocytes from patients with chronic lymphocytic leukemia and ataxia-telangiectasia.

Abnormal cellular interactions between T and B lymphocytes were identified in patients with CLL and AT. The system employed utilized the detection of a newly recognized lymphokine, NIF-T. This mediator is produced by T lymphocytes as a result of the interaction between T and B cells. Our studies demonstrated impaired T cell function but normal B cell activity in patients with AT with respect to mitogenic stimulation and MLC reactivity. In contrast, patients with B cell CLL had normal T cell function. The leukemic B cells from these patients, however, failed to collaborate with normal T cells in response to mitogens, and they did not participate in MLC reactions. In contrast, lymphocytes from patients with HCL functioned normally with respect to NIF-T production.