Both NK Sensitive and Resistant Mycoplasma Free Cell Lines Stimulate Release of NKCF

Abstract

Studies on the NK lytic mechanism in our laboratory have produced evidence that natural killer cytotoxic factors (NKCF) may be the lytic mediators. Our model for the NK lytic mechanism proposes that after binding of the NK cell to the target, the target stimulates the effector to release NKCF (1,2). In support of this, we have found that effector cell populations enriched for NK cells in either human (3) or mouse (4) produce NKCF during coculture with NK sensitive tumor stimulator cells. The objective of this investigation was to determine if there is any NK specificity at the level of induction of NKCF release. Experiments were also carried out to determine if mycoplasma infection of tumor stimulator cells had any effect on the production of cytotoxic supernatants by murine or rat spleen cells. It was found that both NK sensitive and resistant mycoplasma free cell lines could stimulate release of NKCF. Some mycoplasma infected cell lines could generate cytotoxic supernatants, however, it is not clear whether the lytic activity is due to NKCF or some other agent.