Effect of chronic human recombinant erythropoietin therapy on antibody responses to immunization in chronic hemodialysis patients

There are multiple lines of evidence suggesting that human recombinant erythropoietin (rEPO) could influence immune responses by direct effects of rEPO on T or B cells. The present study tested this hypothesis by measuring antibody responses after immunization to tetanus toxoid (TT, a T cell dependent antigen or pneumococcal capsular polysaccharide antigen (PA, a T cell independent antigen). The patients chosen for this prospective study were chronic hemodialysis patients receiving chronic rEPO therapy, and a comparable group of chronic hemodialysis patients not receiving rEPO therapy. We found that the patients immunized with PA and receiving rEPO therapy (N = 15) had IgG anti-PA responses comparable to that of those not receiving rEPO therapy (N = 15). In contrast, in the patients immunized with TT, those receiving rEPO (N = 15) developed significantly higher IgG anti- TT levels than those not receiving rEPO (N = 14) (time-group interaction P =0.005). The peak difference between these groups wits at two weeks, where the rEPO-treated patients developed a 4.1-fold mean increase in IgG anti-TT level and those not receiving rEPO developed only a 1.4-fold mean increase in IgG anti-TT level (P < 0.01). The difference in immune response to TT in the rEPO compared to the non-rEPO-treated patients could not be explained by differences between the groups in any of the parameters measured at baseline or during the post-immunization period. In conclusion, rEPO therapy increased immune response to TT but not PA, which suggests that rEPO enhances immune response to T cell dependent antigens.