Inverse relationship in H-2-associated lysis between NK cells and rIL-2-activated killer cells: evidence from in vitro killing and metastatic experiments

We investigated the manner in which rIL-2 induced effectors in vitro (LAK cells), which, like NK cells, lyse targets nonspecifically and discriminate nonself, and how H-2 as the self-marker affects the LAK cell killing mechanism. NK cells showed an appreciably higher killing activity to B16 melanoma H-2- cells than to H-2+ cells. In contrast, LAK cells lysed more efficiently to H-2+ cells. The in vivo experiments showed that the NK cells prevented pulmonary metastasis of B16 H-2- cells in the normal syngeneic host, whereas the transferred LAK cells had a preferential inhibitory effect on the pulmonary metastasis of B16 H-2+ cells in the immunodeficient syngeneic hosts. Taken together, these results show that the H-2-encoded or H-2-associated molecules contribute to the triggering signal in the lysis by LAK cells, whereas the NK cells recognize the reduced self H-2 expression on the targets, thereby contributing to a trigger of the lysis.