Granulocyte-specific antinuclear factors in serum and synovial fluid in rheumatoid arthritis.

Abstract

Synovial fluids and sera from 50 patients with definite rheumatoid arthritis were investigated for the presence and nuclear specificity of antinuclear factors (ANF) using the fluorescent antibody technique with several human and animal tissues as antigen. The overall incidence of ANF in sera was 64%, and in synovial fluids 62%, but this high incidence was mainly caused by a high prevalence of ANF reactive with the nuclei of polymorphonuclear granulocytes. Thus, while 90% of the ANF-positive sera and 96% of the ANF-positive synovial fluids reacted with the nuclei of granulocytes, a statistically significant smaller number (P <0.01) of sera and synovial fluids reacted with other nuclei tested; these included some of the most common antigens used for the detection of ANF. In accordance with these findings, granu-locyte-specific ANF were found in 12 synovial fluids and in 9 sera. In 25 cases, granulocyte-reactive ANF were found in sera and synovial fluids, while in 16 cases the ANF reaction was negative in sera and synovial fluids. In 5 cases, granulocyte-reactive ANF were found in synovial fluids only, and in 4 cases in sera only. An unexpected correlation occurred between the finding of granulocyte-reactive ANF in synovial fluids and low cell counts. The mean count of granulocytes was approximately 3 times fewer in granulocyte-ANF-positive synovial fluids, while the mean count of mononuclear cells showed no significant difference between ANF-positive and ANF-negative synovial fluids. The mechanism which may be concerned in this correlation is briefly discussed.