Phenotype of cytotoxic effector cells infiltrating a transplanted, chemically induced rat sarcoma.

Previous work from this laboratory indicated that methylcholanthrene-induced sarcomas in the rat are infiltrated by cells with the cytotoxic properties of natural killer (NK) cells. Using a combination of velocity sedimentation and analysis and separation in the fluorescence-activated cell sorter, it has been possible to isolate and characterize these putative NK cells. The present results confirm that cytotoxicity is restricted to NK-sensitive targets (syngeneic, allogeneic and xenogeneic) and no evidence was found for cytotoxic T lymphocytes (CTL). In addition, effector cells have the morphology of large granular lymphocytes, and the pattern of expression of five monoclonal antibody-defined surface markers is identical with that of normal splenic NK cells.