To examine synovial fluid (SF) from patients with arthritis, for the presence of the cytokine leukemia inhibitory factor (LIF).
SF from 152 subjects was examined for LIF, using a radioreceptor competition assay.
LIF was present at concentrations of 1-43 ng/ml in the SF of 23% of patients with rheumatoid arthritis (RA) or other inflammatory or infectious arthritides but in only 1 of 29 patients with osteoarthritis (P < 0.01). In the RA patients, the SF LIF concentration correlated significantly with the peripheral blood white blood cell count (WBC) (P < 0.05) and the SF WBC count (P < 0.01), but not with other clinical or radiologic parameters of disease activity or progression.
LIF is implicated as a potential mediator of the local or systemic inflammatory response or the joint destruction seen in inflammatory arthritis.