Laminin selectively enhances monocyte-macrophage-mediated tumoricidal activity

Recent evidence indicates that laminin may be involved in the phenotypic behavior and metastasis of certain tumor cells. We examined the effect of laminin on monocyte-macrophage killing of two human tumor lines, Malme-3M melanoma and CAK-I renal carcinoma. Laminin enhanced both monocyte- and macrophage-mediated tumoricidal activity against human melanoma cells but did not promote monocyte and macrophage killing of CAK-I renal carcinoma cells. Laminin promoted substratum adherence of melanoma cells in a concentration-dependent manner but had no effect on adhesion of the renal carcinoma cells. The monocyte-macrophage cytotoxicity promoted by laminin paralleled its effects on cell substratum adhesion. In addition to an effect on adhesion, laminin also promoted migration of the melanoma cells but not of the renal carcinoma cells. Laminin did not promote the adhesion of monocytes or macrophages. Laminin may promote monocyte-macrophage tumor cytotoxicity by increasing the interaction of tumor and effector cells through its effect on target or tumor cells.