Effects of copper and zinc on chondrocyte-mononuclear cell adhesion via ICAM-1/CD18 interactions

Abstract

Copper and zinc play important, but as yet undetermined, roles in the function of the immune system and in inflammatory processes. In this study we demonstrated that addition of copper salts to cultures of rat and human articular cartilage and isolated porcine chondrocytes induced expression of the intercellular adhesion molecule, ICAM-1. Expression of this adhesion molecule in response to copper sulphate did not, however, promote adhesion of chondrocytes to peripheral blood mononuclear cells (PBMC), whereas ICAM-1 induced by IL-lα significantly increased cell adhesion. Zinc sulphate, in contrast to copper sulphate, had no effect on ICAM-1 expression on chondrocytes, but was found to upregulate CD18 (LFA-1), the counter-receptor for ICAM-1 on PBMC, thereby increasing the adhesion of PBMC to chondrocytes. The possible consequences of these novel effects of copper and zinc salts on cell membrane molecules are discussed.