Murine NK cell cultures: effects of interleukin-2 and interferon on cell growth and cytotoxic reactivity.

This is the authors' abstract. We don't add key points for this paper.

Murine spleen cell populations were stimulated in vitro with 50 µg of poly l:C and 24 h later, were transferred to medium containing lnterleukin-2 (IL-2). Under these conditions, cytotoxic cells could be maintained indefinitely. Removal of mature T cells at the initiation of culture, by treatment with anti-Thy 1.2 antibody in the presence of complement, was without effect on the development of cytotoxic cells. Cells harvested from such cultures exhibited surface markers characteristic of NK cells (Thy 1 +, asialo GMI +, Lyt 2−). Concordant with the display of NK phenotypic markers, the cytotoxic cells lysed YAC-1 lymphoma cells and an NK-susceptible clone (27v) of the L5178Y lymphoma, but did not lyse clone 27av cells, an NK-insusceptible variant of L5178Y. Studies involving the addition of graded doses of mouse fibroblast interferon (IF) to mouse spleen cells, showed maximal potentiating effects of 103 U/culture, with significantly less augmentation of NK cytotoxicity at higher IF concentrations. When partially purified IL-2 was concomitantly added, IL-2 and IF were at least additive in their effects at all IF concentrations. Several observations suggested that IL-2 itself, like IF, was capable of augmenting NK cell-mediated cytotoxicity. Thus, preparations of IL-2, which lacked IF, caused a rapid increase in NK cell activity. Additionally, the ability to augment cytotoxicity was removed from IL-2 preparations not only by absorption with IL-2 receptor-bearing cells, but also by precipitation with a monoclonal antibody directed against IL-2. One explanation for the cooperation between IF and IL-2 was suggested by the finding that spleen cell population exposed to IF showed a markedly augmented ability to bind IL-2, suggesting that IF may cause an increased display and/or affinity of IL-2 receptors. Furthermore, T cell-depleted spleen cells cultured in IF and IL-2 possessed readily demonstrable Thy 1 antigen, suggesting that these agents either modulate the display of cell surface macromolecules or, perhaps, that they potentiate T cell differentiation in vitro.