1Wafaa El Sadek, 1Mona Lotfy, 2Heba Arnaout, 2Marii Abd El Aziz, 2Amal Balbaa and 3Sherif Amin.
1Anaesthesiology, 2Medical Microbiology & Immunology and 3Clinical Pathology Departments, Faculty of Medicine, Cairo University, Egypt.
Initial resistance to bacterial infection is mediated primarily by polymorphonuclear leucocytes (PMN) before the acquired cellular response is induced. Anaesthetic agents have been reported to impair various aspects of PMN as well as T - cell functions. It is possible that the use of these agents to sedate critically ill patients may further compromise an already depressed host defense mechanism. A flow cytometric technique with fresh whole blood from 10 healthy volunteers was used to study the effect of propofol and midazolam on phagocytic activity of PMN. Blood was incubated for 1 hr. with either propofol or midazolam at both clinical plasma concentration (5 mg, 150 ng / ml respectively) and 100 times this concentration (0.5 mg, 15mg / ml respectively). Then the ability of PMN to phagocytose propidium iodide - labeled Staph. aureus was determined by measuring the mean peak channel fluorescence (MPCF). A non significant difference was found between the untreated control (103.1 + 23.3) and propofol and midazolam treated PMN cells at both clinical plasma concentration (105.5 + 25, 104.5 ± 25.5 for propofol and midazolam respectively) and 100 times this concentration (105.3 ± 25, 104.2 ± 25.2 for propofol and midazolam respectively). The effect of propofol on the number of circulating CD4+ and CD8+ T - cells was also studied in vivo in 20 patients undergoing minor breast surgery. The mean percentage of CD4+ T - cells was significantly higher after propofol anaesthesia (55.5 % ± 10.7) than before anaesthesia (49.2 % ± 12.2) [p < 0.05]. In contrast, no significant effect was noticed on CD8+ - T cells. In conclusion, propofol and midazolam have no depressant action on the phagocytic activity of PMN and propofol does not decrease the number of T cells.