Rheumatoid factor-producing cells detected by direct hemolytic plaque assay.

Abstract

A B S T R A C T Lymphocytes secreting anti-IgG anti- bodies, rheumatoid factors (RF), can be detected in the peripheral bloods, synovial fluids, and bone mar- rows of patients with seropositive rheumatoid arthritis by using a direct plaque-forming cell (PFC) assay with sheep erythrocytes sensitized with reduced and alkylated rabbit IgG hemolysin. The autospecific nature of the RF produced by RF-PFC was indicated by inhibition studies in which the order of potency was human IgG > rabbit IgG > bovine IgG. In metabolic studies puro- mycin, cycloheximide, and vinblastine suppressed RF- PFC. Cyclic AMP and cyclic GMP were without effect. A need was recognized for using full tissue culture media during the cell separation and plaquing procedures to optimize detection of the RF-PFC.