Extracorporeal Irradiation of the Blood

The development and duration of lymphopenia in 71 uremic patients undergoing extracorporeal irradiation of the blood (ECIB) have been investigated. The median duration of each ECIB session was 9 1/2 hours, administered at intervals ranging from 1 to 4 days. The median total duration of one series of ECIB was 100 hours. The changes in the lymphocyte concentration during ECIB were analysed by means of the least squares method and could be expressed by the equation Y = B(1) e (‐ B(2) X) + B(3), in which Y is the lymphocyte count in % of pre‐ECIB level and X the number of blood volumes radiated. The development of lymphopenia was then defined by the slope — B (2) and the degree by the intercept B (3). In all patients a rapid reduction of the lymphocyte concentration in peripheral blood to 25–30% of pre‐ECIB level was observed. Continuation of ECIB treatment did not result in a further significant reduction of the lymphocyte concentration. A direct relationship was found between the transit dose and the development and degree of lymphopenia for transit doses between 100 and 500 rads. Variation neither in blood flow rate nor in spacing of the ECIB sessions had any detectable influence on the development and degree of the lymphopenia produced. After cessation of ECIB the lymphocyte concentration was followed in 19 patients within a period of 18 months. An increase in the lymphocyte counts to 35–40% of pre‐ECIB level was observed within the first 5 months after cessation of ECIB, but from the 5th to the 18th month no further increase could be demonstrated.