Cytotoxicity of Cultured Mouse Spleen Cells against Natural Killer-Sensitive Target Cells

Killer cells with natural killer (NK) cell-like target selectivity were generated when C3H or C57BL/6 mouse spleen cells were cultured in vitro. Compared with NK cells, the in vitro-generated killer cells with NK-like reactivity were slightly adherent to nylon wool fibers, a little more sensitive to anti-Thyl.2 antibody plus complement and almost entirely resistant to cytotoxic treatment with anti-asialo GM1 antiserum which is selectively cytotoxic to NK cells. The culture of NK-depleted spleen cells yielded a lower degree of NK-like cytotoxicity, thus it seems likely that NK cells changed to NK-like killer cells in vitro. Competitive inhibition studies suggested that the in vitro-generated NK-like cells were different from alloantigen-reactive killer T cells. The above results, therefore, might suggest that in vitro-induced NK-like cells do not belong to any known subset of killer cells.