Effect of medication on synovial fluid leukocyte differentials in patients with rheumatoid arthritis

Levels of leukocytes (white blood cells) in synovial (joint) fluid increase in most types of arthritis, and the type of cell can help to determine the extent of inflammatory disease that may be present. Numbers of leukocytes can vary, from an average of 15,000 per cubic millimeter of fluid (mm3) to as high as 100,000/mm3 in some cases of rheumatoid arthritis (RA). In addition, the type of leukocyte is important; higher levels of polymorphonuclear neutrophils (PMNs) are often found in cases of severe acute arthritis. The differences in levels of leukocytes and particularly in levels of lymphocytes (immune cells important in defending against infection and which may mediate tissue destruction in arthritis) were studied in relation to medication taken by 45 patients with RA. The patients had detectable joint effusions (extrusion of fluid, suggestive of continued arthritis in spite of medication), necessitating fluid removal, so that synovial fluid was thus available for analysis. Of 22 patients taking nonsteroidal anti-inflammatory drugs (NSAIDs, which decrease inflammation but do not affect the underlying disease process), 17 had a predominance of lymphocytes in synovial fluid. The proportion and total levels of lymphocytes were significantly lower in patients taking a second-line (disease-modifying) drug such as methotrexate (MTX), gold, or hydroxychloroquine (HCQ). Total leukocyte counts were significantly higher in patients taking MTX or gold than those taking HCQ plus NSAIDs. Among these latter patients, five had taken only NSAIDs at one point and had predominantly lymphocytes in synovial fluid. The report suggests that relative levels of different leukocytes may vary according to therapy given for RA. (Consumer Summary produced by Reliance Medical Information, Inc.)