Serum levels of interleukin-1b, tumour necrosis factor-a and interleukin-2 in rheumatoid arthritis. Correlation with disease activity.

Cytokines are potent immunoregulatory factors and may be directly involved in the disordered immunoregulation found in chronic rheumatic diseases. Interleukin-1b (IL-1b), Interleukin-2 (IL-2) and Tumour Necrosis Factor-a (TNF-a) have been implicated in the pathogenesis of rheumatoid arthritis (RA) as mediators of chronic inflammation. Serum levels of IL-1b and TNF-a measured by radioimmunoassay were significantly higher in patients with RA than in healthy controls of similar sex and age while serum levels of IL-2 were significantly lower in the same patients. Further IL-1b and TNF-a were significantly elevated in RA patients with active disease and IL-2 was significantly reduced when compared with patients with low active disease. Serum IL-1b and TNF-a appear to correlate with systemic inflammation, and systemic features of RA may result from dissemination of cytokines produced in the synovium. The role of IL-2 in RA remains controversial. Reduced levels of IL-2 may be an expression of a deficiency of T-cells to produce IL-2 in the active phases of RA or may be due to a possible absorption of IL-2 by lymphocyte receptors.