Changes of Splenocyte Proliferative Capacity and Subpopulation of Peripheral Lymphocytes Related to the Hemorrhage Amount in Rats

ABSTRACT

BACKGROUND: Hemorrhage itself has been shown to produce abnormalities in immunity, particularly depression of the lymphocyte function. In order to better examine the amount of hemorrhage required to suppress the lymphocyte function, we determined the effect of graded fixed-volume hemorrhage on splenocyte proliferation and the lymphocyte subpopulation. METHODS: Male Sprague-Dawley rats(weight, 350~400g) were anesthetized, subjected to hemorrhages of 7.5ml/kg, 15ml/kg, and 22.5ml/kg by percutaneous cardiac puncture with 26G needles. After 1, 2, 4, and 7 days, animals were killed to obtain the blood and spleen. The splenocyte proliferative capacity was measured by using the tritiated thymidine incorporation technique, and the peripheral lymphocyte subpopulation was determined using flow cytometry with the following monoclonal antibodies T cell(CD3+), T helper cell(CD4+), T cytotoxic cell(CD8+), and B cell(CD45RA+). RESULTS: Hemorrhage of 7.5ml/kg did not induce depression of splenocyte proliferation. However, for hemorrhage greater than 15ml/kg, the splenocyte proliferative capacity was significantly depressed at 2 days after hemorrhage and recovered at 4 days. Hemorrhage induced no changes in the relative percentage of lymphocyte subpopulations and in the number of each cell in peripheral blood. CONCLUSION: This study suggests that cellular immunity is depressed at 48 hrs after a hemorrhage greater than 15ml/kg without any change in the peripheral lymphocyte subpopulation.