Inhibition of in vitro proliferative response of cultured t lymphocytes to interleukin‐2 by gold sodium thiomalate

Gold sodium thiomalate (GST), in concentrations attainable during chrysotherapy for rheumatoid arthritis, significantly inhibited the proliferative responses of cultured T cells stimulated by interleukin-2 (IL-2). The observed suppression was not related to altered kinetics, cell death, or interference with the binding of IL-2 to cell surface receptors. It appeared that GST affected an early step in the proliferative process, since maximum inhibition was obtained by the addition of GST within 4 hours of stimulation; progressive reduction of suppression was observed when GST was added later. Significant inhibition occurred when cultured T cells were preincubated for 24 hours with GST and washed prior to IL-2 stimulation, although the degree of suppression was decreased. Thus, inhibitory activity was not dependent on the continued presence of GST throughout culture. These findings suggest that there is a direct inhibition of T lymphocytes by GST, which may be important in immunomodulation by gold compounds.