MONOSPECIFIC BUT NOT POLYREACTIVE HUMAN HYBRIDOMA RHEUMATOID FACTORS EXHIBIT PREFERENTIAL BINDING SPECIFICITIES FOR IGG3 AND IGG4

Among 38 human hybridoma-derived monoclonal rheumatoid factors (RFs) g enerated from patients with either rheumatoid arthritis (RA) or system ic lupus erythematosus (SLE), two groups of RFs can be identified. Mon ospecific RFs were derived primarily from patients with RA and are cha racterized by a binding specificity for IgG3 and/or IgG4. Polyreactive RFs were derived largely from patients with SLE and show a broader pa ttern of reactivity to all four isotypes of IgG. Neither population of RFs was exclusive to either disease. The binding specificities identi fied appear to be different from the RFs isolated from patients with m ixed cryoglobulinemia and may reflect a different antigen selection me chanism.