Occurrence of interleukin-1 in human synovial fluid: detection by RIA, bioassay and presence of bioassay-inhibiting factors

Abstract

Synovial fluid (SF) from patients with osteoarthritis (OA), rheumatoid arthritis (RA), and various other arthridites was analyzed to assess the prevalence of interleukin-1 (IL-1) using both radioimmunoassay competitive inhibition specific for the beta form of IL-1 and the D10.G4.1 cell line bioassay which measures both alpha and beta forms of IL-1. Using radioimmunoassay competitive inhibition, IL-1 beta was found in 45% and 60% of individual samples from patients with OA and RA respectively. When RA and OA SF were examined in sequentially obtained samples, IL-1 beta occurred in one or more samples from 8 of 10 patients studied, suggesting the probability that it can be produced at some time in SF by all patients with these conditions. No correlation between SF leukocyte counts and the occurrence of IL-1 beta was noted and no effect of antiinflammatory drug treatment on the prevalence of IL-1 beta was found. When tested for the presence of IL-1 by the D10.G4-1 cell line, 66% and 50% of RA and OA patients respectively were found to contain IL-1. These were not in total concordance with results obtained by RIA. Of all SF tested, seven were negative by RIA but positive by D10.G4.1 and these are considered to contain IL-1 alpha. Seven samples which were RIA positive and D10.G4.1 negative were tested for their ability to inhibit IL-1 responses in the bioassay. Five of these contained inhibitor and one markedly enhanced the proliferative response of D10.G4.1 to a known amount of IL-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Phenotypic Characterization of Inflammatory Cells from Osteoarthritic Synovium and Synovial Fluids

“…Numerous investigators have reported finding IL-1 in synovial fluid specimens from many arthropathies, including OA (14 -16), and the range of the IL-1 levels seen in OA patients was similar to that seen in rheumatoid arthritis (RA) patients. In our study, IL-1␤ was present in 54% of OA synovial fluids and 41% of RA synovial fluids (16). A similar study from our laboratory documented the presence of macrophage-colony-stimulating factor (M-CSF) in OA synovial fluids (17).…”

“…To examine OA-associated inflammation earlier in the disease process, we studied synovial fluids collected by arthrocentesis. Earlier work from our laboratory found both IL-1␤ and M-CSF in OA synovial fluids (16,17). Here we assayed for TNF-␣, an important mediator of inflammation in rheumatoid synovium, and IL-6, a cytokine whose levels in knee synovial fluids has been correlated with inflammatory infiltrates (26).…”

Insulin-like growth factor (IGF) receptor, IGF-I, interleukin-1 beta (IL-1 beta), and IL-6 mRNA expression in osteoarthritic and normal human cartilage.

“…The mediator is a potent stimulator of proteoglycan degradation and an inhibitor of proteoglycan synthesis in cartilage explants, leading to rapid net depletion of this matrix molecule (35)(36)(37). In addition, IL1 has been detected in the synovial fluid from patients with OA (38)(39)(40). IL1 mRNA has also been demonstrated in isolated human articular chondrocytes from one individual (41) and in cultured rabbit chondrocytes (42).…”

A Factor Derived from Polymorphonuclear Leukocytes Enhances Interleukin‐1‐Induced Synovial Cell Collagenase and Prostaglandin E2 Production in Rats

“…IL-1, one of the main factors which stimulate collagenase and PGE, production by mesenchymal cells such as joint synovial fibroblasts (Dayer et al, 1986), is known to be prestnt in rheumatoid synovial fluid (Smith et a]., 1989;di Giovini: and Duff, 1990;Rooney et al, 1990;Westacott et al, 1990;Fong et al, 1994), but precise assay has been hampered by interfering components in synovial fluid.…”