Immunological features in chronic lymphocytic leukaemia (CLL) of T cell origin.

Peripheral blood lymphocytes from a patient with chronic lymphocytic leukaemia of T cell origin were studied. The thymus derived nature of these lymphocytes was confirmed by surface markers, mitogen cultures, mixed lymphocyte reaction, cytotoxicity studies, and cytochemical stains. This case is notable for several clinical and laboratory findings. Among these, the benign clinical course, the reduced rate of serum immunoglobulins, the elevated number of active E rosettes, the increased PHA-induced response to low mitogen doses, the absence of PHA mediated cellular cytotoxicity, and the thy-like positivity to ANAE should be pointed out. Emphasis should be placed, however, on the loss of stimulatory ability in MLR. This last feature supports the hypothesis that these cells proliferate as a clone.