Elevation of Circulating ??-Endorphin Levels with Concomitant Depression of Immune Parameters after Traumatic Injury

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Abstract
Immunosuppression is frequently observed after traumatic injury, and is associated with the subsequent development of sepsis. Although a number of factors such as age, nutritional status, and the degree of injury have been related to the severity of the immunosuppression that occurs, the physiologic alterations leading to immunosuppression are not well defined. We hypothesized that changes in the endogenous opiate peptides, such as .beta.-endorphin, might contribute to changes in the immune system following injury. Levels of circulating .beta.-endorphin, responsiveness to the mitogen PHA, and the frequency of circulating T11, T4, and T8 cells were measured in trauma patients hospitalized in a surgical intensive care unit. .beta.-endorphin levels were elevated during the first 4 days after trauma (134.1 .+-. 22.5 vs. 49.3 .+-. 4.3 pg/ml, mean .+-. S.E., patient vs. control; p < 0.001). During the same time period patient PHA response (10,852 .+-. 3,775 vs. 28,147 .+-. 12,078; p < 0.05), and the per cent of T4 positive (31.2 .+-. 2.6 vs. 47.0 .+-. 1.4; p < 0.001) cells were lower than controls. These parameters were not significantly different from control values when measured at later times. Thus we conclude there is a temporal association of depressed immune parameters and elevated .beta.-endorphin levels after traumatic injury.