Synthesis of electrophoretically restricted IgG by cultured rheumatoid synovium.

IgG synthesized by excised rheumatoid (RA) synovia was separated according to isoelectric point using chromatofocusing and isoelectric focusing. Over 30% of the IgG synthesized by 9 of 11 synovia had an isoelectric point greater than 8 (cathodal shift), while 55% of the synovia secreted IgG showing oligoclonal banding by isoelectric focusing. Oligoclonal serum IgG was seen in 17% of RA patients and in only 3% of hospitalized patients without RA. These results emphasize the selective character of the antigenic stimulus of the RA synovial lymphoid infiltrate.