Biological effects of ionizing radiation on human blood compounds ex vivo

Purpose: Blood compounds are irradiated ex vivo to prevent transfusion-associated graft-versus-host-disease. Recently, ex vivo irradiation of re-transfused wound blood has been proposed to prevent metastatic spread in patients with malignant tumors, an issue requiring different dose concepts. To determine effects on blood cells we examined the impact of various doses of ionizing radiation. Methods: Full blood was irradiated with doses of 10-150 Gy. Potassium, LDH and hemoglobin levels were determined 2 h-96 h after irradiation. The lymphocyte proliferation after irradiation was measured by means of a lymphocyte-transformation assay. The impact of irradiation on mitogen-induced secretion of cytokines was determined by the ELISA technique, and P-selectin expression as an indicator of platelet activation was analyzed by flow-cytometry. Results: Potassium levels increase with aging and irradiation dose. Mitogenic capacity is reduced by over 90% with moderate doses of 10-20 Gy, but a residual proliferation is still detectable up to 50 Gy. No enhancement of extracellular cytokine levels is detectable, but the cytokine release is reduced by radiation. Neither induction of platelet activation nor abrogation of activation has been detected. Conclusions: Doses of 3050 Gy abrogate lymphocyte proliferation almost completely. In this range we did not observe severe adverse effects on blood transfusions. Hemolysis might be enhanced when the samples are stored for a longer period after irradiation.