Generation of CFU-C suppressor T cells in vitro. III. Failure of mitogen-primed T cells from patients with chronic granulocytic leukemia to inhibit the growth of normal CFU-C.

T lymphocytes were derived by E rosetting from the peripheral blood (PB) and bone marrow (BM) of 15 patients with chronic granulocytic leukemia (CGL) in the chronic phase of their disease. T cells were also obtained from 12 healthy individuals. T cells were incubated overnight either in culture medium (RPMI) or RPMI plus pokeweed mitogen (PWM). The supernatants were then recovered and the cells washed in fresh RPMI. T cells from normal donors and from CGL patients were then cocultured with normal allogeneic marrow cells grown in soft agar for CFU-C colony formation. Target marrow cells were also grown in agar in the presence of T-derived supernatants. The results of this study can be summarized as follows. (1) Normal PB and BM T cells efficiently suppressed autologous and allogeneic CFU-C growth after PWM stimulation. (2) T cells derived from peripheral blood or marrow of CGL patients failed to inhibit CFU-C growth, whether pretreated with PWM or not. (3) The supernatants of PWM-treated normal T cells strongly inhibited CFU-C colony formation, whereas the supernatants of PWM-treated CGL T cells had no CFU-C/suppressor activity. These data indicate that T cells from CGL patients cannot be primed to become CFU-C suppressor cells after PWM: stimulation in vitro and cannot release a soluble inhibitor of granulopoiesis produced by PWM-primed normal T cells.