The restoration of proliferation and differentiation of peripheral blood mononuclear non-adherent cells into immunoglobulin-secreting cells by autologous synovial adherent cells from patients with rheumatoid arthritis

The ability of enzyme-dissociated synovial adherent cells (SAC) obtained from patients with active rheumatoid arthritis to restore the proliferation and differention of peripheral blood mononuclear non-adherent cells (NAC) into immunoglobulin-secreting cells (ISC) was investigated. Autologous combinations of cells were used in this study to eliminate allogeneic reactions. Peripheral blood NAC, prepared by glass adherence and leucine methylester treatment to remove monocytes, almost completely lost their capacity to proliferate and differentiate into ISC in response to pokeweed mitogen. The response of NAC was restored by adding 12.5% of 'fresh SAC', which was obtained by glass-adherence after an overnight culture of non-rosette forming, enzyme-dissociated rheumatoid synovial cells. Although the response was also restorable by adding more than 25% fresh SAC, this was less satisfactory than adding 12.5% SAC. 'Old SAC', obtained by glass-adherence after 7 days culture of enzyme-dissociated synovial cells, did not restore the response of NAC. Immunohistochemical studies showed that 55% of fresh SAC and 3% of old SAC expressed HLA-DR antigens. When 100 units/ml of interferon gamma was present, 25% of old SAC remained HLA-DR-positive and some of these cells retained a dendritic morphology after 7 days culture. The results indicate that rheumatoid synovia contain macrophage-like cells that can effectively support the ultimate differentiation of lymphocytes to ISC.