Human monoclonal IgG rheumatoid factors from the synovial tissue of patients with rheumatoid arthritis.

We have established IgG rheumatoid factor (RF)-secreting hybridoma cell lines from the synovial tissues of two patients (TS and SJ) with rheumatoid arthritis (RA) and one (KL) with the polyarticular form of juvenile rheumatoid arthritis (JRA). The IgG RF bind human and rabbit IgG and all except one form intracellular complement-fixing complexes indicative of a self-association process. The possibility of IgG RF for self association and immune complex formation is a feature thought to be important for the inflammatory processes in RA. Of the IgG RF-secreting cell lines established, three clones from patient SJ and one from patient KL are of the IgG1 kappa isotype while five clones from patient TS are of the IgG2 lambda isotype.