– To assess whether beta-2 microglobulin (B2M) has effects on articular chondrocytes that would implicate B2M involvement in osteoarthritis (OA) pathogenesis.The average B2M level in OA synovial fluid is significantly higher than that found in normal synovial fluid. B2M is highly expressed in OA cartilage and synovial fluid compared to normal, and suggest that B2M may have effects on chondrocyte function that could contribute to OA pathogenesis.