The adoptive transfer of lymphokine-activated killer (LAK) cells in conjunction with the systemic administration of recombinant interleukin 2 (RIL-2) results in the regression of established pulmonary and hepatic micrometastases from a variety of immunogenic and nonimmunogenic murine tumors in syngeneic C57BL/6 mice. Recent studies have shown that this therapeutic approach can mediate the regression of cancer in humans as well. Because of the practical difficulties in obtaining syngeneic or autologous LAK cells for the therapy of cancer in humans we have now evaluated the antitumor efficacy of allogeneic LAK cells generated from different strains of mice. The in vitro lysis of fresh tumor targets by LAK cells is not a major histocompatibility complex-restricted phenomenon since LAK cells of BALB/c-H-2d, DBA/2-H-2d, and C3H-H-2k origin all exhibited lytic activity when tested against allogeneic MCA-102-H-2b tumor cells in short term 51Cr release assays. In vivo, the i.v. transfer of allogeneic LAK cells combined with i.p. injections of RIL-2 reduced the number of established pulmonary metastases induced by either MCA-105 or MCA-101 tumors which are syngeneic to C57BL/6 hosts. The extent of reduction of these pulmonary metastases by the allogeneic LAK cells was directly dependent upon the dose of RIL-2 given; increasing doses of systemically administered RIL-2 resulted in increasingly greater reduction in the numbers of established 3-day pulmonary sarcoma metastases. In dose titration experiments, adoptive transfer of at least 2 doses of 10(8) allogeneic LAK cells was necessary to achieve significant antitumor effect in vivo. Allogeneic LAK cells were also successful in mediating significant regression of hepatic micrometastases. Again, the i.v. transfer of allogeneic LAK cells had a smaller therapeutic benefit compared to i.v. transfer of syngeneic LAK cells. When allogeneic LAK cells were injected intraportally, however, they were as effective as syngeneic LAK cells. Allogeneic LAK cells had little, if any, therapeutic effect on established pulmonary and hepatic metastases when administered to recipients previously immunized to the histocompatibility antigens on the donor cells. Taken together, our results indicate that allogeneic LAK cells from several strains of mice are effective in lysing fresh MCA-102 tumor in vitro and that when given i.v. in sufficient numbers, in conjunction with RIL-2, they can mediate significant reduction in the number of established pulmonary and hepatic micrometastases in nonalloimmunized C57BL/6 mice.(ABSTRACT TRUNCATED AT 400 WORDS)