Functional characterization of NK1.1(+) Ly-6C(+) cells

It was found that NK1.1(+) cells were subdivided by their different expression pattern of Ly-6C antigen. To characterize their functional significance in immunoregulation, we separated NK1.1(+)Ly6C(+) cells and NK1.1(+)Ly-6C(-) cells from C57BL/6 mouse nylon-passed spleen cells by FACStar. Both NK1.1(+)Ly-6C(+) and NK1.1(+)Ly-6C(-) cells responded to the stimulation with IL-2 plus IL-12 and showed strong cytotoxicity against YAC-1 cells. However, these cells revealed different ability in terms of IFN-gamma production. Only NK1.1(+)Ly-6C(+) cells, but not NK1.1(+)Ly-6C(-) cells, cultured with IL-12 alone or IL-2 plus IL-12, produced high levels of IFN-gamma. Flow cytometric analysis demonstrated that NK1.1(+)Ly-6C(+) cells consisted of NK1.1(+)CD3(-)Ly-6C(+) NK cells and NK1.1(+)CD3(+)Ly-6C(+) NKT cells. Therefore, we further separated these two populations from NK1.1(+)Ly-6C(+) cells to define their functions. Although, both NK1.1(+)CD3(-)Ly-6C(+) NK cells and NK1.1(+)CD3(+) NKT cells showed the same level of cytotoxicity. It was clearly demonstrated that NK1.1(+)CD3(+)Ly-6C(+) NKT cells were major immunoregulatory cells to produce IFN-gamma in respond to IL-12 alone or IL-2 plus IL-12. Copyright (C) 1996 Elsevier Science B.V.