Syngeneic tumor cells can induce alloreactive T killer cells: a biological role for transplantation antigens.

A chemically induced sarcoma of BALB/c (H-2d) mice, MCG4, is shown to induce in BALB/c lymphocytes a primary anti-tumor cytolytic T lymphocyte (CTL) reaction in vitro. The anti-tumor CTL showed tumor specificity but reacted also with normal cells expressing distinct H-2 alloantigens. The CTL response could be shown to be induced by and directed against alloantigenic determinants expressed on two different molecules, one H-2Kk-like the other H-2Dk-like. The biological significance of these findings is discussed with regard to (i) possibility of derepression of normally silent H-2 genes in tumor cells and normal cells, (ii) generation of alloreactivity in ontogeny, and (iii) role of alloreactive T cells in eliminating cells expressing wrong gH-2 antigens.