Interleukin 1 receptor antagonist inhibits the augmentation of metastasis induced by interleukin 1 or lipopolysaccharide in a human melanoma/nude mouse system.

This study examined the ability of the recombinant human interleukin 1 receptor antagonist (IL-1ra) to block interleukin 1 (IL-1)-mediated experimental metastases from the A375M human melanoma. In vivo, IL-1ra administrated at concentrations > or = 200 times IL-1 significantly inhibited the increase in lung colonies induced by IL-1 in nude mice. The response to IL-1 was significantly inhibited when IL-1ra was administered simultaneously with or 1 to 3 h before IL-1. In vitro, the incubation of IL-1-activated endothelial cells with IL-1ra prevented the increase in adhesion of A375M melanoma cells. At the same experimental conditions, IL-1ra inhibited the augmented expression of the intracellular and vascular cell adhesion molecules 1 and E-selectin induced by IL-1 on endothelial cells. Lipopolysaccharide, an IL-1 inducer, increased the number of lung colonies in nude mice. IL-1ra injected with or 1 h after lipopolysaccharide inhibited this augmentation, suggesting a role for host-produced IL-1 in metastasis formation.