Inactivation of C1 in rheumatoid synovial fluid, purfied C1 and C1 esterase, by gold compounds.

Abstract

The effects of gold compounds on the functional activities of rheumatoid synovial fluid and normal serum Cl, C4, and C2 were investigated in vitro. Commercial and purified gold sodium thiomalate in concentrations, as low as 1·25 μg/ml (expressed as elemental gold) inactivated native C[unk] and highly purified C[unk]s, whereas equivalent or higher concentrations of thiomalate had no effect. C[unk] inactivation was caused also by other gold compounds such as gold chloride and gold sodium thiosulphate. The C[unk] inactivation was not reversible following extensive dialysis. The partial protection of C4 and C2, the two natural substrates for C[unk], indirectly verified the C[unk] inactivation. This is the first study to show that gold compounds inactivate C[unk], one of the reactants in the pathogenesis and/or perpetuation of rheumatoid arthritis.