Immunotherapy in rheumatoid arthritis by T-suppressor lymphocytes: experimental model in vitro

In this study, the immunoregulation of IgG and IgM synthesis by synovial fluid lymphocytes (SFL) in rheumatoid arthritis (RA) was investigated. A group of 15 sero-positive rheumatoids with a level of lymphocytes in the joint effusion fluids greater than 40% were selected. In 20 experiments, Con A stimulated peripheral blood lymphocytes (PBL) suppressed Ig synthesis by autologous SFL, tested in the presence and absence of pokeweed mitogen. Mean inhibition value for IgG production was 70.5% +/- 7.1 and for IgM 64.8% +/- 7.5. There were significant differences in the numbers of IgG and IgM producing cells compared to that of controls (p less than 0.001). In contrast, SFLs preactivated with Con A had little suppressive effect; but when SFL's suppressor cells were co-cultured with PBL in a diffusion chamber (used as model for the human joint), they were able to decrease Ig synthesis. The highest inhibition was induced when SFL were pre-incubated with allogeneic PBL from healthy donors. Mean decreases were 514 counts per minute (CPM) for IgG and 486 CPM for IgM compared to control values, almost 50% of the total spontaneous production. These results indicate that the impairment of the suppressor function is restricted to the site of inflammation and can be corrected by PBL. The data hints that intra-articular immunotherapy may have potential therapeutic value.