Antigenic profile of murine natural killer cells.

We have determined the antigenic profile of natural killer (NK) cells from C57BL/6 mice that have lytic activity to RLmale1 tumor cells, in a 5-hr 51Cr release assay. To perform the antigenic typing more effectively, we enriched the NK populations by using discontinous BSA density gradient and established a correlation between NK activity and NK-1 antigen in each layer. As NK activity and Nk-1 antigen are both criteria for measuring NK cells, we determined the antigenic profile of NK cells by monitoring both the change in NK activity and NK-1 cells, after elimination of cells with various antisera to lymphocytic alloantigens. We have found that all NK cells expressed Nk-1, Qa-4, and Qa-5 antigens; about 50% of NK cells expressed Thy-1 and Qa-2 antigens, and 25% of NK cells also expressed Lyt-1 antigen. NK cells did not express significant amounts of Qa-1, Qa-3, Lyt-2, and Lyb-2 antigens. Therefore, spontaneous NK cells are heterogeneous with regard to their surface antigens, some of which are T cell antigens. However, the present antigenic profile does not allow us to classify NK cells in the conventional T cells lineage.