Defective radioresistant suppressor cell activity in hemodialysis patients

The immunologic alterations in patients on hemodialysis are only partially understood. We studied the Concanavalin A (Con A) induced suppressor cell activity of irradiated and nonirradiated cells in a mixed lymphocyte culture. Peripheral blood lymphocytes from 18 normal individuals and 14 patients on regular hemodialysis were incubated with two different concentrations of Con A (10 micrograms and 40 micrograms of Con A/million cells). Irradiated and nonirradiated cells were then tested for their capacity to suppress a standard MLC. The proliferative response to phytohemagglutinin, pokeweed mitogen and Con A was also determined. Suppressor cell activity of nonirradiated cells in hemodialysis patients was similar to that of controls, at both concentrations of Con A, while irradiated cells of hemodialysis patients showed a suppressor cell activity significantly lower than that of the controls, at a Con A concentration of 40 micrograms/10(6) cells (25.78 +/- 18.86% vs. 46.05 +/- 9.79%, p less than 0.001). The proliferative response of lymphocytes from hemodialysis patients to the three mitogens, did not show any difference when compared with normal controls. The normal proliferative response of lymphocytes from hemodialysis patients to mitogens and the normal suppressor cell activity of nonirradiated cells, suggest a normal T cell function. The abnormal suppressor cell activity in irradiated cells indicate that the radioresistant population has a functional defect. The cell responsible for this suppressor defect probably belongs to the monocyte/macrophage population because of its relative radioresistance.