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There is a constant need for clinical diagnostic systems that enable to predict disease course for preventative medicine. Apoptosis, programmed cell death, is the end point of the cell's response to different induction and leads to changes in the cell morphology that can be rapidly detected by optical systems. We tested whether apoptosis of T-cells in the peripheral blood is useful as predictor and compared different preparation and analytical techniques. Surgical trauma is associated with elevated apoptosis of circulating leukocytes. Increased apoptosis leads to partial removal of immune competent cells and could therefore in part be responsible for reduced immune defence. Cardiovascular surgery with but not without cardiopulmonary bypass (CPB) induces transient immunosuppression. Its effect on T-cell apoptosis has not been shown yet. Flow-cytometric data of blood samples from 107 children (age 3-16 yr.) who underwent cardiac surgery with (78) or without (29) CPB were analysed. Apoptotic T-lymphocytes were detected based on light scatter and surface antigen (CD45/CD3) expression (ClinExpImmunol2000;120:454). Results were compared to staining with CD3 antibodies alone and in the absence of antibodies. T-cell apoptosis rate was comparable when detected with CD45/CD3 or CD3 alone, however not in the absence of CD3. Patients with but not without CPB surgery had elevated lymphocyte apoptosis. T-cell apoptosis increased from 0.47% (baseline) to 0.97% (1 day postoperatively). In CPB patients with complication 1.10% significantly higher (ANOVA p=0.01) comparing to CPB patients without complications. Quantitation of circulating apoptotic cells based on light scatter seems an interesting new parameter for diagnosis. Increased apoptosis of circulating lymphocytes and neutrophils further contributes to the immune suppressive response to surgery with CPB. (Support: MP, Deutsche Herzstiftung, Frankfurt, Germany)
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