Production of leukemia inhibitory factor by human articular chondrocytes and cartilage in response to interleukin-1 and tumor necrosis factor α

Objective. To investigate the production of leukemia inhibitory factor (LIF) by human articular chondrocytes and cartilage. Methods. Chondrocytes and cartilage were cultured with and without added cytokines, and the conditioned media assayed for LIF by a specific radioreceptor competition assay. Results. Interleukin-1 (IL-1) and tumor necrosis factor α (TNFα) stimulated LIF production by chondrocyte monolayers and cartilage. LIF was generally not detected in unstimulated cultures. Northern blot analysis showed increased amounts of LIF messenger RNA in IL-1– and TNFα-treated chondrocyte cultures. Conclusion. Chondrocytes, stimulated by IL-1 and/or TNFα, are potential contributors to the elevated levels of LIF observed in the synovial fluids of patients with rheumatoid arthritis and other inflammatory arthritides.