Calcitriol therapy modulates the cellular immune responses in hemodialysispatients

We studied the in vitro and in vivo effects of calcitriol (1,25D) on the ce llular immune responses in 19 hemodialysis (HD) patients. In vitro 5-day tr eatment with 1,25D markedly reduced the HLA-DR expression by peripheral blo od CD14(+) monocytes from both HD patients and normal subjects in a similar fashion, The HLA-DR expression by monocytes and the phorbol myristate acet ate (PMA)induced superoxide production (SOP) by neutrophils were significan tly higher in the HD patients than in the normal subjects (p < 0.01 and p < 0,05, respectively). The phagocytic activity in the HD patients was signif icantly lower than that in the normal subjects (p < 0,05), Moreover, the mi togen response of HD peripheral blood lymphocytes against pokeweed mitogen (PWM) was significantly lower than that of the controls (p < 0.01) but was only slightly and insignificantly lower against Con A. Oral 1,25D pulse the rapy resulted in a marked decrease in the HLA-DR expression by peripheral b lood monocytes 2 and 4 days after the first 1,25D administration (p < 0.01) in HD patients. Moreover, the treatment significantly enhanced the PMA-ind uced SOP 2 days after the treatment(p < 0.01). However, the phagocytic acti vity by neutrophils and the mitogen responses to Con A and PWM by lymphocyt es were not significantly affected by this treatment, These results suggest that 1,25D plays a significant role in the regulation of both the monocyte and neutrophil functions in HD patients. Copyright (C) 2000 S. Karger AG,B asel.