In rheumatoid arthritis, during active joint inflammation, synovial fluid is turbid, yellow, and sterile, and usually has white blood cell counts 10, 000 to 50, 000 / mcL (10.0 x10 9 / L to 50.0 x10 9 / L); polymorphonuclear leukocytes typically predominate, but > 50% may be lymphocytes and other mononuclear cells.