50 Trakia Journal of Sciences, Vol. 12, Suppl. 1, 2014 Trakia Journal of Sciences, Vol. 12, Suppl. 1, pp 50-54, 2014 Copyright © 2014 Trakia University Available online at: http://www.uni-sz.bg ISSN 1313-7050 (print) ISSN 1313-3551 (online) CHANGES IN PERIPHERAL BLOOD LYMPHOCYTE POPULATIONS IN PATIENTS WITH ACUTE PANCREATITIS K. Halacheva 1* , G. Minkov 2 , Y. Yovtchev 2 , T. Denev 1 1 Department of Molecular Biology, Immunology and Medical Genetics, Medical Faculty, Trakia University, Stara Zagora, Bulgaria 2 Department of Surgery, University Hospital, Stara Zagora, Bulgaria ABSTRACT We tested peripheral blood total lymphocyte and lymphocyte subsets in 32 consecutive acute pancreatitis patients (18 women and 14 man; age 33-80 years, median 63 years)) studied at admission, as well as, at 48h and on day 5 of hospitalization, using a flow cytometric analysis. Seventeen healthy subjects comparable for sex and age were studied as controls. On admission the percentage of total lymphocyte, CD3+ T cells and CD4+ T cells was significantly decreased in patients with acute pancreatitis as compared to controls but was significantly increased at 48h and on day 5 with respect to those on admission. Conversely, the percentage of CD8+ T cells in patients was significantly decreased compared to controls at all points of investigation. The percentage of CD56+ NK cells was increased in patients on admission, but significantly decreased on day 5 compared to those on admission and to controls, as well. The percentage of activated CD3+ CD25+T cells, CD4+CD25+ T cells and CD8+CD25+ T cells was significantly increased compared to controls at all points of investigation. We conclude that cell-mediated immunity was compromised in the early stage of acute pancreatitis, along with significant activation of T lymphocytes, especially T helpers cells. Key words: Acute pancreatitis, Flow cytometry, Lymphocytes, T cells INTRODUCTION Acute pancreatitis (AP) is an acute inflammatory disease of the pancreas, with variable involvement of peripancreatic tissues and remote organ systems depend on severity of disease. The clinical presentation of AP varies from a relatively mild, self-limiting disorder to severe disease with development of multiple organ failure. (1-5). Excessive inflammatory reaction is considered to contribute to the development of organ failure as a leading cause of complications in early AP. (6, 7). It is characterized by systemic release of pro- inflammatory cytokines (8). The systemic inflammation is accompanied by development of an anti-inflammatory reaction that results in high ________________________ *Correspondence to: Krasimira Halacheva, Department of Molecular Biology, Immunology and Medical Genetics, Medical Faculty, 11 Armeiska str, 6000 Stara Zagora, Bulgaria, E-mail: khalacheva@mf.uni-sz.bg. serum levels of anti-inflammatory cytokines (9) followed by immunosuppression with infectious complications in the late phase of AP. Cause inflammatory character, the involvement of immune system in the pathogenesis of AP constitutes an important study area. Lymphocytes play a central role in the modulation of the inflammatory reactions in different disease, including AP (10). Several studies have reported a reduction of the peripheral lymphocyte count as well as CD3+, CD4+, CD8+ CD20+ and CD3+DR+ lymphocytes in acute pancreatitis ( 11- 24). T cell activation has been demonstrated in AP by expression of activation markers CD25 (20) and CD69 (18). Ueda et al. 2006 (21) have demonstrated that the CD4+ T helper cell type 1/type2 (Th1/Th2) balance tends to Th1 suppression in experimental severe AP and suggest that immunosuppression may occur from the early phase in patients with AP. Moreover,