Apoptosis of lymphocytes in SLE: the level, correlation with prednisolone dosage and lymphocyte phenotypes

Introduction: SLE is a systemic autoimmune disorder. One of the mechanisms by which elimination of autoreactive lymphocytes takes place is apoptosis. Adefect in apoptosis may thus contribute to the development of autoimmune disease. Patients and methods: The study included 34 Russian children patients with SLE in age between 6-17 years old. Lymphocytes were isolated from venous blood by method of gradient centrifugation of all the blood through a Ficoll-pak solution. The quantity apoptotic cells was determined in leukocytes by flow cytometry Epics XL-2 (“Beckman Coulter”, USA). Analysis of lymphocyte subpopulations was carried by using two fluorescent labels: FITC conjugated monoclonal antibodies (CD-25 and CD-20) and phycoerythrin conjugated monoclonal antibody (CD-3, CD-4 and CD-8). Results: After in vitro incubation in CO2 incubator for 36hr; the percentage of apoptotic lymphocytes from patients with SLE was significantly higher than from healthy donors (7.2* ± 4.7 % vs. 5.5 ± 3.2% respectively). This was found to be depending upon the SLE disease activity. Moreover, observed correlations between level apoptosis lymphocyte in SLE and the titer of antibodies to dsDNA (r = 0.5) and dosage prednisolone (r = 0.6). By analyzing lymphocyte phenotypes; there was no significant difference in percentage of CD3+T-cells from SLE compared to normal donors (62.4±7.2 vs. 68.7±9.9.); the same had been observed in CD8+ T-cells (20.9±5.5 vs. 25.3±5.6); and in CD20+ B-cells (9.7±8.9 vs. 13.7±8.0). However, the percentage of CD4+T cell was significantly decreased (P = 0,001) in patients with SLE compared to normal donors (25.5*±7.3 vs. 40.6±8.7). The immunoregulatory index was decreased in SLE compared to normal donors (1.2 vs 1.6 respectively). This phenotypes disbalance was associated with significant increased in the level of activated CD25+ lymphocytes in SLE compared to normal healthy donors. Keywords: SLE, apoptosis, lymphocyte phenotypes, prednisolone, dsDNA autoantibodies, flow cytometry Sudan Journal of Medical Sciences Vol. 1(1) 2006: 14-1