Text Box: APOPTOSIS OF PERIPHERAL BLOOD LYMPHOCYTES FROM CHILDREN WITH JUVENILE CHRONIC ARTHRITIS Smolewska E.1, Brozik H.1, Biernacka M.1, Wyka K.2, Smolewski P.3, Darzynkiewicz Z.4, Stanczyk J.1 1Department of Pediatrics Cardiology and 2Department of Immunopathology Institute of Pediatric Medical University of Lodz, Poland 3Department of Haematology Medical University of Lodz, Poland 4Brander Cancer Research Institute, NYMC, USA Objective: The aim of this study was to evaluate apoptosis in peripheral blood lymphocytes from children with juvenile chronic arthritis (JCA). Methods: The study has been performed in 29 children with JCA and 15 healthy subjects as controls. After isolation, the lymphocytes were cytocentrifuged on microscope slides. Two methods of identification of apoptotic cells were used. The first was based on the in situ detection of DNA strand breaks using the APO-BRDU kit. The second method relied on the immunocytochemical detection of (ADP-ribose) polymerase (PARP) cleavage product p89 PARP. Cell fluorescence was measured by a laser scanning cytometer. The serum level of circulating sFAS was evaluated using the ELISA assay. Results: The mean percent of lymphocytes with apoptosis in JCA children was higher then in control (p=0.461). Surprisingly, the mean level of sFAS was also slightly higher in JCA children, but the difference was not statistically significant (p=0.112). However, there was no correlation between ratio of apoptosis, and sFAS levels. The highest apoptotic ratio has been found in JCA children with high activity of the disease (p=0.016) and the generalization of joints involvement at the diagnosis (p=0.001). These results were correlated well some of the inflammatory indicators, such as SR and serum CRP levels. Conclusion: Our data indicates activation of apoptosis in peripheral blood lymphocytes from children with highly active and advanced JCA. Mechanisms of induction of apoptosis may be at least partially independent of the apo1/Fas receptor pathway. 2329