INCREASED LEVELS OF LEUKEMIA INHIBITORY FACTOR IN SYNOVIAL-FLUID FROMPATIENTS WITH RHEUMATOID-ARTHRITIS AND OTHER INFLAMMATORY ARTHRITIDES

Objective. To examine svnovial fluid (SF) from patients with arthritis , for the presence of the cytokine leukemia inhibitory factor (LIF). M ethods. SF from 152 subjects was examined for LIF, using a radiorecept or competition assay. Results. LIF was present at concentrations of 1- 43 ng/ml in the SF of 23% of patients with rheumatoid arthritis (RA) o r other inflammatory or infectious arthritides but in only 1 of 29 pat ients with osteoarthritis (P < 0.01). In the RA patients, the SF LIF c oncentration 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. Conclusion. LIF is implicated as a potential mediator of the local or systemic inflammatory response or the joint destructio n seen in inflammatory arthritis.