To study the Ig genes that encode IgG rheumatoid factor (IgG-RF) from rheumatoid synovial fluid.
We used rheumatoid synovial fluid B cells to generate IgG-RF-secreting hybridomas. We then characterized their binding properties and determined their nucleotide sequences.
Two monospecific IgG-RFs were obtained. Sequence analysis of the RFs revealed a new V lambda gene family (designated V lambda 9) and extensive somatic diversification, including a duplication-insertion of 18 nucleotides (6 amino acid residues) into a hypervariable region.
The data provide further support for an antigen-driven response in the sustained production of potentially pathogenic IgG-RFs in rheumatoid synovium.