A 40-year-old woman with rheumatoid arthritis has sustained joint inflammation despite methotrexate therapy. Synovial biopsy shows dense plasma cell and lymphocyte infiltrates with lymphoid follicle formation. Elevated levels of which cytokine in synovial fluid best explains the persistence of synovitis and activation of osteoclasts causing joint erosion?

• A TNF-alpha ✓
• B IL-10
• C TGF-beta
• D IL-35

Explanation

TNF-alpha is the dominant pro-inflammatory cytokine in rheumatoid synovitis, produced by activated macrophages and synoviocytes. It sustains synovial inflammation by upregulating ICAM-1, stimulating IL-1 and IL-6 production, and — critically — promoting osteoclastogenesis by upregulating RANKL, driving bone erosion. This is the mechanistic basis for the therapeutic efficacy of TNF inhibitors (etanercept, adalimumab, infliximab) in RA. IL-10 and TGF-beta are anti-inflammatory cytokines.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.