Bucillamine inhibits T cell adhesion to human endothelial cells

We investigated the ability of bucillamine [N-(2-mercapto-2-methyl-propionyl)-L-cysteine] to prevent T cell adhesion to endothelial cells (EC) isolated from human umbilical vein. When EC were pretreated with bucillamine, T cell binding to the EC was suppressed in a dose dependent fashion. The T cells could bind preferentially to recombinant interferon-gamma (rIFN-gamma) treated EC compared with untreated EC. Bucillamine could also suppress T cell binding to rIFN-gamma treated EC as well as untreated EC. Addition of copper sulfate to bucillamine decreased significantly the percent T cell adhesion to the EC compared with bucillamine alone. The magnitude of inhibition by bucillamine and copper sulfate was similar in EC treated with rIFN-gamma as well as in untreated EC. H2O2 also inhibited the T cell binding to both untreated and rIFN-gamma treated EC. The inhibitory effects of bucillamine with or without copper sulfate on T cell binding to EC were abolished completely by catalase but not by superoxide dismutase. Our results suggest that hydrogen peroxide generated by bucillamine, with or without copper sulfate, inhibits T cell binding to EC. We believe, therefore, that bucillamine may suppress inflammation, such as that in rheumatoid synovitis, by reducing the emigration of chronic inflammatory cells from capillaries into tissue.