Extracorporeal Irradiation of the Blood

Abstract

During the last three years a total of 80 patients have received extracorporeal irradiation of the blood (ECIB) prior to kidney transplantation. The irradiators were developed and fabricated by the Danish Atomic Energy Commission, Risø. The main data from three types of equipment—stationary and mobile gamma units and portable beta units—are presented. For the total material the average duration of ECIB was 103 h, the mean transit dose 295 rads and the mean total dose 42 850 rads. The lymphocyte concentration was reduced from 1 350 + 526 before to 335 + 122 after ECIB. According to the transit dose the patients were divided into three groups. Group I (20 patients) received a mean transit dose of 96 rads, and a mean total dose of 21 680 rads. Group II (21 patients) received a mean transit dose of 359 rads and an average total dose of 50 100 rads. Group III (20 patients) received an average transit dose of 432 rads and an average total dose of 54 420 rads. The rate of development of lymphopenia was significantly slower in group I than in groups II and III, but reduction of the lymphocyte concentration to the same degree (about 30% of pretreatment value) was observed in all three groups. At 15 000 rads the percentual reduction was significantly larger in group I than in groups II and III. There was no correlation between flow rate, calculated as the number of patients' blood volumes radiated per hour, and the rate of development of lymphopenia. After cessation of ECIB the lymphocyte concentration was followed in those patients who were not transplanted immediately. In 9 patients belonging to groups II and III the concentration remained constant at 30% of pretreatment value during the first 8 months. At 12 months it had increased to 50%. In 6 patients, belonging to group I, the lymphocyte concentration increased to 50% three months after cessation of ECIB. The practical conclusion of the present study is that a prolonged lymphocyte reduction is obtained with ECIB, with high transit doses resulting in high total radiation doses which caused hemolysis. If the total radiation doses are reduced by reduction of transit doses (100 rads), lymphopenia is obtained without hemolysis, but ECIB has to be repeated at more frequent intervals in order to maintain lymphopenia.