[Prevention of post-transfusion graft versus host disease by irradiating blood products with X-ray or gamma-ray].

Irradiation of blood products is an effective way to prevent post-transfusion graft versus host disease (PT-GVHD). We examined the mitotic activity of lymphocytes in blood products with the aid of 3H-thymidine uptake after irradiation with various doses of X-ray. The results showed the mixed lymphocyte culture (MLC) response was completely abolished by irradiation with only 5 Gy. Irradiation with 50 Gy completely eliminated mitogen-stimulated 3H-thymidine uptake (Mitogen response). The risk of PT-GVHD would be eliminated by irradiation with over 15 Gy, because MLC response seems to reflect closely the mechanism of PT-GVHD in patients. Furthermore, it was shown that X-ray irradiation with up to 50 Gy has no deleterious effects on in vitro characteristics of blood products. However, we must pay attention to the high concentration of potassium in the plasma of blood products stored after irradiation.