Stimulatory ability of human leukaemic cells in the allogeneic mixed leucocyte reaction.

Cryopreserved mononuclear cells from 34 patients with a high proportion of blasts in the peripheral blood were tested for their ability to stimulate normal allogeneic lymphocytes in the one-way mixed leucocyte reaction (MLR). Of these, more than half failed to stimulate allogeneic responders, despite the fact that many of them carried Ia-like antigens. In general, acute myeloid leukaemia cells were non-stimulatory whereas acute myelomonocytic leukaemia cells were effective stimulators. Thus, MLR stimulatory ability appears to be a differentiation marker in acute non-lymphocytic leukaemias. Acute lymphocytic leukaemia cells were divided between the two categories, although this division did not parallel conventional classification. As reported by other workers, chronic lymphocytic leukaemia cells were non-stimulatory. The implications of these results for host-leukaemia relationships are discussed.