Arginase release from red blood cells: Possible link in transfusion induced immune suppression?

Arginine stimulates lymphocyte function and is degraded by arginase, an enz yme that is abundantly present in red blood cells. Arginase impairs lymphoc yte function and responses in vitro. Leakage of arginase from stored red bl ood cells may be involved in the lymphocyte dysfunction associated in allog enic blood transfusion. In the present study, arginase activity was determi ned in bags of red cells stored for transfusion. Buffy coat depleted red bl ood cells were obtained routinely from four healthy donors and stored In ba gs for a maximum period of five weeks at 4 degreesC. The bags were sampled for determination of arginase, lactate dehydrogenase, and potassium. In add ition, a random sample of 36 bags of red blood cells about to be transfused to patients were studied. Levels of arg[nase, lactate dehydrogenase, and p otassium showed a time dependent increase in the bags of the four donors. T his time dependent increase in arg[nase activity could be confirmed in the additional bags sampled (P < 0.0001, r = 0.78). The results for the first t ime show that arginase is released from red blood cells during storage for transfusion. Arginase infusion may play an important role in the Immune sup pression observed after blood transfusion.