V‐GENE Repertoire and Hypermutation of Rheumatoid Factors Produced in Rheumatoid Synovial Inflammation and Immunized Healthy Donorsa

We have compared RF from normal, immunized donors and RF derived from the synovial tissues of RA patients. We have found a difference in the preferential use of VL and VH gene families. In both conditions, RFs were found to have accumulated somatic mutations. However, there was a striking difference in the patterns of mutation. RFs from normals were characterized by a very low R:S ratio in the CDR1+2, considerably lower than seen among the RARFs. In addition, there was little increase in affinity with increasing numbers of mutations in a group of clonally related RFs from an immunized normal. This contrasts with RF from RA, where there is evidence of both affinity maturation and class switching. Together these data suggest that in healthy persons there is a controlling mechanism to limit the affinity of RF autoantibodies, and that this is lost in RA. The higher affinity of the RA-derived RF may be of significance in the pathology of the disease.