The effect of gold sodium thiomalate and auranofin on lipopolysaccharide-induced interleukin-1 production by blood monocytes in vitro: variation in healthy subjects and patients with arthritis.

The anti-rheumatic gold compounds gold sodium thiomalate (GST) and auranofin (AF) have variable and often unpredictable effects in patients treated for arthritis. As inhibition of interleukin-1 (IL-1) production may be an important effect of these drugs, we investigated their effect on IL-1 production by lipopolysaccharide (LPS) stimulated monocytes in a serum-free, non-adherent culture system. A bi-modal effect was observed: low concentrations (GST 10-250 ng/ml and AF 1-100 ng/ml) potentiated IL-1 production, and higher concentrations (GST 200-1000 ng/ml and AF10-500 ng/ml) inhibited it. This bi-modal effect was observed for both secreted and cell-associated IL-1 activity with the exception that GST failed to inhibit cell-associated IL-1 generation. The potentiating effect was dependent on the continuous presence of gold for at least the first few hours after LPS stimulation. The inhibitory effect of GST was dependent on its presence after LPS stimulation while that of AF was evident even if cells were pretreated with AF and washed before exposure to LPS. There was considerable individual variation in IL-1 production in response to LPS as well as in the effects of gold on cells from both healthy individuals and patients with arthritis. There was also some overlap in the range of concentrations of gold that potentiated and inhibited IL-1 production, and there was relative insensitivity to the inhibitory effects of gold in certain individuals. These results may explain some of the variability in the response of patients to chrysotherapy and support further studies to see if these in vitro effects might predict clinical response to gold.