Modulation by IFN-gamma of the metastatic ability of murine, human, and H-2-transfected tumor cells.

Interferon-gamma (IFN-gamma) can enhance the experimental metastatic ability of B16 melanoma. The in vitro treatment with IFN-gamma of four clones derived from the murine mammary adenocarcinoma TS/A increased the number of lung colonies observed after intravenous injection in syngeneic mice. The spontaneous metastatic ability of these clones was not altered by the IFN-gamma pretreatment nor by daily intratumor injection of low-dose IFN-gamma. The experimental metastatic ability in nude mice of the human rhabdomyosarcoma cell line RD was decreased by in vitro pretreatment with IFN-gamma. To study the role played by major histocompatibility complex gene products in the IFN-gamma-mediated enhancement of B16 experimental metastasis, a mutant B16 clone, B78H1, was transfected with the H-2Kb gene. B78H1 cells are not capable of expressing H-2b even after treatment with IFN-gamma; IFN-gamma readily induced high levels of H-2Kb in a set of transfected clones, but did not enhance their experimental metastatic ability.