Objective. Nitric oxide (NO) is a free radical involved in inflammation and immune reactions. The presence of NO is usually assessed by assaying its degradation products, nitrite and nitrate. NO binds to thiol‐containing proteins to form S‐nitrosoproteins (S‐NP). The aim of this study was to investigate the presence of S‐NP, together with nitrite and nitrate, in patients with rheumatoid arthritis (RA). Methods. Forty patients with RA were studied and compared with 24 patients with osteoarthritis (OA) and 21 control subjects. Fourteen patients were treated with 3 consecutive pulses of methylprednisolone for flares of RA. Nitrite was measured by the Griess reaction, and nitrate by a spectrophotometric assay using nitrate reductase. Spectrofluorometry coupled with the inner filter effect was used for the measurement of S‐NP. Results. S‐NP was detected in all RA samples, both in serum and synovial fluid (SF). Serum and articular S‐NP concentrations were correlated ( P < 0.03). In RA, nitrite and S‐NP levels were higher in SF than in serum; higher SF levels of the 3 compounds were observed in RA than in OA. S‐NP levels in RA patients decreased significantly ( P < 0.03) after pulse methylprednisolone treatment, in parallel with the clinical improvement. Conclusion. S‐NP, a biologically active form of NO, was consistently present in RA, with higher concentrations within the arthritic joint. S‐NP assays should be added to nitrite and nitrate assays for the evaluation of NO metabolism. S‐NP could be a stable storage form of active NO in RA, and its measurement could be useful in evaluating pharmacologic interventions that modulate NO generation.

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This study demonstrates the potential role of NO for the induction of synoviocyte apoptosis in OA. The increased expression of p53 in the nucleus may play a protective role in the control of apoptosis.

Elevation of serum interleukin-1 beta (IL-1 beta) levels, and to a lesser degree tumor necrosis factor alpha levels, was found in cachectic human immunodeficiency virus (HIV)-infected African patients without concurrent opportunistic infection or neoplasia (HIV wasting syndrome). A heterogeneous pattern of elevations of cytokine levels, including mild elevations of IL-1 beta and pronounced elevations of IL-6 levels, was found in other cachectic states.