Relation of H-2 expression on murine RCT(+) sarcoma cells to lung colonization and sensitivity to NK cells.

Murine RCT(+) sarcoma cells were sorted using a fluorescence-activated cell sorter with regard to the expression of H-2 antigens and then an increased H-2-expressing subclone was established, and named RCT(+)H-2+. The experimental metastasis of RCT(+) cells was compared with that of RCT(+)H-2+ cells by counting pulmonary colonies on the 21st day after i.v. inoculation of tumor cells (5–10×104/mouse). When mice were inoculated with RCT(+) cells, mean numbers of pulmonary colonies were 2.1(range 0–6), 2.8(range 0–7) using 5×104 and 1×105 cells, respectively. On the other hand, in the mice inoculated with RCT(+)H-2+ cells, figures obtained were 7.0(range 4–16), 31.9(range 13–79), using 5×104 and 1×105 cells, respectively. The survival rate of RCT(+)H-2+ cells was higher than that of RCT(+) cells, when this was assayed in the early stage after i.v. injection of 51Cr-labeled cells (1×105 cells/mouse). In addition, RCT(+)H-2+ cells were more resistant than RCT(+) cells to lysis mediated by natural killer cells. These data suggest that an increase in metastatic ability was paralleled by an increase in the H-2 antigen expression and a decrease in sensitivity to the natural killer cells.