Activation of Fc receptor-bearing lymphocytes by immune complexes. II. Killer lymphocytes mediate Fc ligand-induced lymphokine production

Cells that participate in immune complex-induced production of leukocyte migration inhibitory factor (LIF) activity can be concentrated in a population making up 2-4% of human peripheral blood lymphocytes in which greater than 90% of the cells are active in a single cell antibody-dependent cellular cytotoxicity assay. When so concentrated, such killer (K) cell preparations are as efficient in producing LIF activity as mitogen activated T lymphocytes. Other Fc receptor (FcR)-bearing lymphocytes, including natural killer (NK) cells, do not produce measurable LIF activity when incubated with immune complexes (additional evidence that the K and NK cells among ligands to the FcR of the appropriate lymphocytes, possibly without need for exogenous receptor bridging, is the only requirement for their activation to immune complex-induced lymphokine production (ICLP). It is probable that ICLP by K cells palays a role in antibody-mediated effector functions in vivo.