The immunosuppressive effect of extracorporeal irradiation of the blood evaluated by blast transformation and membrane immune fluorescence tests.

The immunosuppressive effect of extracorporeal irradiation of the blood was investigated by in vitro blast transformation tests on circulating lymphocytes and on lymphocytes isolated from lymph nodes and by B-lymphocyte counts before, during, and after the treatment. Two consecutive patient series, from a controlled clinical trial of the effect of extracorporeal irradiation of the blood on the course of kidney transplantation, were studied. B-cell depeltion was found to be relatively larger than the total lymphocyte depletion. In vitro transformation tests on both circulating and lymph node lymphocytes showed large individual variations. There were no characteristic correlations between the results of these tests or with the number of circulating lymphocytes. Nor were there any characteristic changes in these tests during treatment. These results, together with previous experience, seem to contraindicate the value of irradiation of the blood as an immunosuppressive treatment.