Lymphocyte subsets in hemodialysis patients treated with recombinant human erythropoietin.

We investigated whether recombinant human erythropoietin (rhEPO) therapy affected the lymphocyte subsets in patients on long-term maintenance hemodialysis (HD) with severe anemia. Before treatment, the numbers of peripheral blood lymphocyte, CD3+, CD4+, CD8+, and CD20+ cells were decreased in HD patients compared to those in healthy subjects, while the number of CD3+HLA-DR+ cells was increased in HD patients compared to that in healthy subjects. Furthermore, the number of CD4+CD45RA+ (naive T) cells was markedly decreased in HD patients (112 +/- 77 vs 241 +/- 146/microliters; P < 0.01). The number of CD8+S6F1+ (cytotoxic T) cells in HD patients was also less than that in healthy subjects (247 +/- 104 vs 122 +/- 83/microliters; NS). During a 6-month period of rhEPO therapy, we found that the low level of CD4+CD45RA+ cells gradually increased (from 112 +/- 18 to 163 +/- 24/microliters; P < 0.01) with the elevation of hematocrit values (from 21.5 +/- 1.7 to 28.2 +/- 3.5%; P < 0.05). The number of CD3+HLA-DR+ cells decreased after 1 month of rhEPO therapy (from 93 +/- 14 to 46 +/- 13/microliters) and gradually declined throughout the 6-month study period. In our in vitro study, we demonstrated that no effects were observed on [3H]thymidine uptake in the T cell subsets at various concentrations of rhEPO. These results suggest that rhEPO-induced immunoregulation is mediated by an indirect stimulatory effect on the immune system, this stimulation being accompanied by an improvement in physical condition.