Quantitation of cells secreting immunoglobulins after elution from rheumatoid synovial tissue

Mononuclear cells (MNC) eluted from rheumatoid synovial tissue of 16 patients with rheumatoid arthritis were examined for immunoglobulin-secreting cells (ISC). Immediately after elution and separation synovial tissue MNC contained considerable numbers of ISC. IgG and IgA ISC were more abundant than IgM ISC. At the same time there were low numbers of ISC in blood. Synovial tissue ISC were lost during incubation with pokeweek mitogen (PWM), possibly because tissue MNC were already maximally triggered in vivo. This was in contrast to blood MNC, in which the number of ISC increased significantly during incubation with PWM.