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

Arginine stimulates lymphocyte function and is degraded by arginase, an enzyme that is abundantly present in red blood cells. Arginase impairs lymphocyte function and responses in vitro. Leakage of arginase from stored red blood cells may be involved in the lymphocyte dysfunction associated in allogenic blood transfusion. In the present study, arginase activity was determined in bags of red cells stored for transfusion. Buffy coat depleted red blood cells were obtained routinely from four healthy donors and stored in bags for a maximum period of five weeks at 4 degrees C. The bags were sampled for determination of arginase, lactate dehydrogenase, and potassium. In addition, a random sample of 36 bags of red blood cells about to be transfused to patients were studied. Levels of arginase, lactate dehydrogenase, and potassium showed a time dependent increase in the bags of the four donors. This time dependent increase in arginase activity could be confirmed in the additional bags sampled (P < 0.0001, r = 0.78). The results for the first time show that arginase is released from red blood cells during storage for transfusion. Arginase infusion may play an important role in the immune suppression observed after blood transfusion.