Immunoglobulin gene expression in rheumatoid arthritis.

Rheumatoid arthritis (RA) is characterized by inflammation of synovium, in which immunoglobulin-secreting plasma cells are generally present. The forces driving immunoglobulin expression in RA synovium are unknown. Sequences of VH and VK transcripts from an RA synovial cDNA library demonstrate patterns of somatic mutation typical of an antigen-driven response. Moreover, 5% of the kappa repertoire appears to derive from the same B cell progenitor, suggesting an oligoclonal response. Immunoglobulin expression in this synovium thus appears to result from antigen stimulation. In addition, this patient's synovium is enriched for unusually long VK-JK joins (CDR3s), suggesting abnormal selection or regulation of the B cell response in RA.