Phorbol ester treated chronic B lymphocytic leukaemia cells induce autologous T cell proliferation without generation of cytotoxic T cells.

The ability of the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) to modify the stimulatory capacity of leukaemic B cells in autologous mixed leucocyte reactions (AMLR) was studied. T lymphocytes from patients with chronic lymphocytic leukaemia (CLL) did not proliferate when stimulated with untreated autologous non-T cells. In contrast, vigorous 3H-thymidine incorporation was seen in six of eight cases when CLL stimulator cells were pre-incubated for 3 days with TPA. No cytotoxic T cells against TPA treated or untreated autologous target cells were generated in such AMLR. These results indicate that enhancement of AMLR stimulatory capacity may be among the characteristic features of TPA driven in vitro differentiation of CLL cells.