Interleukin 1 (IL-1), IL-6, and tumour necrosis factor (TNF) a are pleiotropic cytokines produced predominantly by macrophages which have been implicated in the pathogenesis of rheumatoid arthritis (RA). Sulphasalazine has been shown to have disease modifying properties and to inhibit the production of cytokines in vitro. To evaluate the effect of sulphasalazine on cytokine production in vivo, serum cytokine levels were measured in a group of patients with RA entered into a randomised controlled trial. Serum levels of IL-la, IL-1,B, IL-6, and TNF a were measured at baseline and at two monthly intervals for six months in 17 patients receiving sulphasalazine and in 22 patients treated with placebo. The two groups of patients had a similar age and sex distribution, had had RA for less than a year, had no joint erosions, and had not been treated previously with any other disease modifying drugs.In the 39 patients studied IL-la was detected (>0.1 ng/ml) at baseline in 14 patients (median 0-24 ng/ml), IL-1,B in 25 patients (median 1-0 ng/ml), TNF a in 27 patients (median 1.2 ng/ml), and IL-6 in 33 patients (median 0.44 ng/ml). In the group treated with sulphasalazine there was a progressive and signficant decline in senrm IL-la, IL-1,B, and TNF a levels over the six month period (median levels at six months were <0-1, 0-12, and 0.44 ng/ml respectively). Interleukin 6 levels were significantly reduced only at the four month time point (median level of 0-23 ng/ml). These reductions were associated with improvements in clinical and laboratory measures of disease activity. In contrast patients receiving the placebo showed no changes in serum cytokine levels and no improvement in clinical and laboratory indices of disease activity. These results suggest that sulphalazne may exert its disease modifying effect partly by suppressing cytokine production in vivo. (Ann Rheum Dis 1992; 51: 946-950)

SUMMARYThe effects of GM-CSF, IL-2, IFN-y. TNF-a and IL-6 on the production of IL-I (both secreted and cell associated) and TNF-a by peripheral blood monocytes were studied. Monocytes were cultured for 20 h in suspension and in serum-free conditions which minimized background stimulation of monokine production. GM-CSF. IL-2 and TNF-a directly induced the production of cell-associated IL-1 but liUlcornoIL-l or TNF-a secretion. Combination of GM-CSF with !FN-y. IL-2 or TNF-a synergistically enhanced IL-1 secretion and had an additive eflect on cell-associated IL-1 production. Combination of IL-2 with IFN-7 or TNF-a also synergistically enhanced IL-I secretion but theefiect on cell-associated IL-I production was less than additive. GM-CSF synergistically enhaneed TNF-a secretion induced by IFN-y but not by lipopolysaccharide. GM-CSF did not enhanee TNF-a secretion induced by IL-2 or TNF-a. In contrast. IL-2 syncrgisticatly enhanced TNF-a seeretion induced by IFN--/. These results are discussed in relation lo cytokine involvement in rheumatoid arthritis.