Morphologic alterations in cultured human synovial fibroblasts induced by blood mononuclear cells

Effects of peripheral blood mononuclear cells on cultured synovial fibroblasts were studied. When mononuclear cells from normal or rheumatoid blood were incubated on synovial fibroblast cultures, a part of the cells adhered to the fibroblasts. They were mainly T lymphocytes but also some B lymphocytes and monocytes. After a 10-hour incubation, adhered mononuclear cells induced morphologic alterations to synovial fibroblasts: appearance of stellate cells and thinning and branching of fibroblasts. No changes were seen when the cells were incubated in the presence of indomethacin. Cytotoxicity of peripheral blood mononuclear cells from 8 rheumatoid patients was also tested against three rheumatoid and three normal synovial fibroblast strains. Only 2 out of 48 combinations were cytotoxic. The potentially cytotoxic mononuclear cells were bound equally well to rheumatoid and control synovial fibroblast cultures.