Abstract
Cytotoxic cells which lack major histocompatibility restriction for lysis are generated when murine spleen cells are cultured in the presence of FCSAbbreviations: AK, activated killer; C′, complement; CTL, cytotoxic T lymphocyte; FCS, fetal calf serum; IFN, interferon; IL‐2, interleukin‐2; MHC, major histocompatibility complex; NC, natural cytotoxic; NK, natural killer; NCMC, natural cellmediated cytotoxicity; NMS, normal mouse serum; MAb, monoclonal antibody.
with or without allogeneic stimulation. The studies reported show that, following 3 days of culture with FCS, murine spleen cell cultures contain at least two cytotoxic populations. The first (AK‐YAC), expresses an NK cell phenotype and target specificity while the second (AK‐WEHI) shares the characteristics of the NC cell. Generation of the AK‐YAC effector cell requires the presence of a pre‐AK cytotoxic cell (Qa‐5, LYT‐2‐plus;) and is dependent on the generation of interleukin‐2 (IL‐2) during the culture period, while the AK‐WEHI effector is independent of IL‐2 production. IL‐2 production in the cultures is shown to require syngeneic la recognition by an Lyt‐1^+^, L3T4^+^ T cell. These findings suggest a role for IL‐2 in the in vivo regulation of NCMC and describe a mechanism for its production in the absence of antigenic stimulation.