Tumour necrosis factor-beta modulates human neutrophil-mediated cartilage damage

Human neutrophils, when cultured with human articular cartilage coated with heat-aggregated immunoglobulin G, degraded proteoglycan and inhibited its synthesis. Neutrophil-mediated degradation of cartilage was potentiated by recombinant human tumour necrosis factor-beta (TNF beta), although TNF beta alone did not alter proteoglycan degradation. This effect was seen when TNF beta, neutrophils, and cartilage were incubated together, and also when neutrophils were preincubated with TNF beta and washed before being added to cartilage. Similar results were obtained with living and killed cartilage. In contrast, pretreatment of neutrophils with TNF beta abrogated the neutrophil-mediated inhibition of proteoglycan biosynthesis. There was no effect of TNF beta alone on synthesis of proteoglycan.