Rheumatoid factor-producing cells detected by direct hemolytic plaque assay

Area of Science:

• Immunology
• Rheumatology

Background:

• Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation.
• Rheumatoid factors (RFs) are autoantibodies commonly found in RA patients.
• Detecting RF-secreting lymphocytes (RF-PFC) aids in understanding RA pathogenesis.

Purpose of the Study:

• To investigate the presence and characteristics of RF-PFC in patients with seropositive rheumatoid arthritis.
• To explore the potential origin and behavior of RF-PFC in different bodily fluids and during disease activity.
• To assess the impact of therapeutic interventions on RF-PFC levels.

Main Methods:

• Direct plaque-forming cell (PFC) assay using sensitized sheep erythrocytes.
• Inhibition studies with various IgG subclasses to determine RF specificity.
• Metabolic inhibition studies using cytotoxic drugs and signaling molecules.
• Optimization of cell separation and plaquing procedures using tissue culture media.

Main Results:

• RF-PFC were detected in peripheral blood, synovial fluid, and bone marrow of RA patients.
• RFs produced by RF-PFC demonstrated autospecificity, with a preference for human IgG.
• Metabolic inhibitors (puromycin, cycloheximide, venblastine) suppressed RF-PFC activity, while cyclic nucleotides had no effect.
• RF-PFC levels fluctuated in peripheral blood, often correlating with disease activity, and decreased with cytotoxic therapy.

Conclusions:

• The presence of RF-PFC in peripheral blood may represent an anamnestic immune response to transient antigens.
• Bone marrow is suggested as a potential site of origin for RF-PFC.
• Optimized detection methods are crucial for accurate RF-PFC assessment.