Predominance of synovial fluid lymphocytes in early rheumatoid arthritis

Evaluation of 158 synovial fluids, mainly from patients with rheumatoid arthritis (RA) and the crystal deposition fiseases (CDD), revealed differences in the differential white blood count and numbers of cytoplasmic inclusion bodies (CIB) present. Lymphocytes and CIB were increased in RA, suggesting a different pathologic mechanism from that of CDD. Lymphocyte-like cells contained CIB implying phagocytic capability. Lymphocytes were the initial predominant cell type in RA of less than six weeks disease duration. Later polymorphonuclear leukocytes increased, possibily representing a secondary non-specific inflammatory response similar to that seen in CDD.