Enhanced T helper cell function for the spontaneous production of IgM rheumatoid factor in vitro in rheumatoid arthritis.

Co-culture experiments between T and B cells from normal subjects and rheumatoid arthritis (RA) patients were performed in order to assess the immunoregulatory effects of T cells on spontaneous production of IgM rheumatoid factor (IgM-RF). Cultures of normal B cells with normal, autologous or allogeneic T cells failed to synthesize IgM-RF. In contrast, RAT cells promoted IgM-RF production from normal B cells as well as from RA B cells. The 'helper' effect of T cells from RA patients for IgM-RF production was not HLA-DR4 restricted and could not be accounted for by an allogeneic effect. These observations suggest that activated T helper cells may contribute to the production of IgM-RF in RA.