Characterization of the cloned rheumatoid synovial cells in long-term culture.

Characterization of the heterogenous synovial cells is pivotal to understand the pathogenesis of rheumatoid arthritis. Three different types of cloned rheumatoid synovial cells; dendritic, macrophage-like and fibroblast-like cells classified by morphology have been cultured for up to 8 months without any significant morphological changes. All three types of the cells were mononuclear adherent cells, and HLA-DR positive when stimulated with γ-interferon. Macrophage-like cells phagocytosed large numbers of carbon particles and fibroblast-like cells did to lesser degree while dendritic cells did not. Spontaneous production of interleukin 1-like factor by three different types of the cells have been detected even after the long-term culture, and the ability was in the following order: dendritic cell> macrophage-like cell>fibroblast-like cell.The results may suggest that majority of the synovial cells could produce interleukin 1-like factor and were responsible for the bony destruction in rheumatoid arthritis.