Activation of lymphocyte subpopulations in patients with chronic lymphocytic leukemia.

T lymphocytes from the peripheral blood of normal donors and patients with CLL were isolated by nylon wool filtration or E-rosette separation and tested for functional activities. Unseparated CLL lymphocytes showed a poor response to phytomitogens and to allogeneic cells. Subpopulations enriched in E-RFC showed an increased PHA- and a normal MLC-reactivity; the Con A responses, however, were markedly reduced in all experiments. Subpopulations which were T cell depleted showed no reactivity to all mitogens. Purified T cells from normal donors showed a decreased reactivity to PHA, Con A and PWM. The Con A responses were completely abolished in almost all experiments. These diminished responses could be restored by unseparated cells or by small numbers of syngeneic, mitomycin-treated monocytes. The data suggest that mitogen-induced T lymphocyte stimulation in vitro in general depends on the presence of monocytes.