INTERLEUKIN-1-ALPHA, INTERLEUKIN-2, AND SOLUBLE INTERLEUKIN-2 RECEPTORS IN POLYMYOSITIS

Cell‐mediated immunity has been implicated in the pathogenesis of polymyositis (PM). We conducted a prospective study in which serum levels of soluble interleukin‐2 receptors (IL‐2R), IL‐1α, and IL‐2 were correlated with creatine kinase (CK) levels and clinical disease activity. Cytokines and IL‐2R were quantitated in 133 serum samples from 14 patients by use of an enzyme‐linked immunosorbent assay. In patients with acute PM (9 patients), soluble IL‐2R and IL‐1α levels were elevated initially, but declined rapidly with therapy. A significant linear relationship was found between soluble IL‐2R levels and CK levels. IL‐2 was initially detectable in only 3 patients, and it disappeared with therapy in all 3. The levels of cytokines and IL‐2R were consistently normal in patients with inactive PM (2 patients). In patients with chronic PM (3 patients), the cytokines and soluble IL‐2R levels were normal despite persistently abnormal CK levels and/or muscle weakness. Cellular IL‐2R levels correlated positively with serum levels of soluble IL‐2R. Our studies substantiate a pathogenic role for cellular immunity in PM, with the finding of activation of lymphocytes. The finding of increased levels of IL‐1α demonstrates for the first time that there is monocyte activation in PM. Persistent elevation of CK levels after normalization of the levels of cytokines and IL‐2R may be prognostic of impending chronic disease. Serum soluble IL‐2R appear to be a sensitive indicator of improvement or exacerbation of disease activity in patients with PM. Copyright © 1990 American College of Rheumatology