OBJECTIVE: To investigate the effect of a new immunosuppressant, FK506, on interleukin 6 (IL-6) production by freshly prepared rheumatoid synovial cells. METHODS: Rheumatoid synovial cells were isolated from synovial tissue of patients with rheumatoid arthritis (RA) by using collagenase and DNase treatment. The surface phenotypes of the cells were analyzed by 2-color fluorescent analysis with FACScan. The levels of IL-6 in supernatant of cultured synovial cells were measured by enzyme immunoassay. RESULTS: The synovial cells used were mainly composed 32 +/- 1% of HLA-DR+/LeuM3+ cells and 53 +/- 6% of HLA-DR-/LeuM3-cells. These synovial cells spontaneously produced a large amount of IL-6 in culture. This spontaneous production of IL-6 was significantly inhibited by FK506 at the concentration of 10(-8) to 10(-6) M in a dose dependent manner. In the preincubation study, FK506 required more than 12 h to inhibit IL-6 production by synovial cells. CONCLUSION: These results suggest that FK506 may be beneficial for patients with RA via inhibiting IL-6 production in inflammatory joints.
OBJECTIVE: To investigate the effect of a new immunosuppressant, FK506, on interleukin 6 (IL-6) production by freshly prepared rheumatoid synovial cells. METHODS:Rheumatoid synovial cells were isolated from synovial tissue of patients with rheumatoid arthritis (RA) by using collagenase and DNase treatment. The surface phenotypes of the cells were analyzed by 2-color fluorescent analysis with FACScan. The levels of IL-6 in supernatant of cultured synovial cells were measured by enzyme immunoassay. RESULTS: The synovial cells used were mainly composed 32 +/- 1% of HLA-DR+/LeuM3+ cells and 53 +/- 6% of HLA-DR-/LeuM3-cells. These synovial cells spontaneously produced a large amount of IL-6 in culture. This spontaneous production of IL-6 was significantly inhibited by FK506 at the concentration of 10(-8) to 10(-6) M in a dose dependent manner. In the preincubation study, FK506 required more than 12 h to inhibit IL-6 production by synovial cells. CONCLUSION: These results suggest that FK506 may be beneficial for patients with RA via inhibiting IL-6 production in inflammatory joints.