Differential expression of two major cytokines produced by neutrophils, interleukin‐8 and the interleukin‐1 receptor antagonist, in neutrophils isolated from the synovial fluid and peripheral blood of patients with rheumatoid arthritis

Abstract

Objective. Neutrophils have been shown to produce interleukin‐8 (IL‐8) and interleukin‐1 receptor antagonist (IL‐1ra) in large amounts compared with other cytokines. Since IL‐8 has a proinflammatory action whereas IL‐1ra is antiinflammatory, our objective was to examine the relative levels of production of these cytokines by synovial fluid (SF) neutrophils isolated from patients with rheumatoid arthritis (RA). Methods. We measured cytokine production using an enzyme‐linked immunosorbent assay and analyzed messenger RNA accumulation in cells by Northern blot. Results. SF neutrophils produced significantly more IL‐8 and IL‐1β, but significantly less IL‐1ra, than peripheral blood neutrophils. Conclusion. These observations provide new information on the production of pro‐ and antiinflammatory molecules by neutrophils in the SF environment, and their possible role in RA.