Comparison of effects of calcitriol and calcium carbonate on secretion of interleukin-1 beta and tumour necrosis factor-alpha by uraemic peripheral blood mononuclear cells.

We studied 26 non-dialysed patients with chronic renal failure [creatinine clearance (CCr) 32.6 +/- 12.7 ml/min]. They were divided into three groups according to their CCr and serum intact parathyroid hormone (PTH) and were given 0.5 micrograms/day oral calcitriol (calcitriol group, n = 8), 3 g/day calcium carbonate (CaCO3 group, n = 10), or neither (control uraemic group, n = 8). Serum intact PTH decreased from 154 +/- 75 to 90 +/- 43 pg/ml in the calcitriol group (P < 0.01) and from 162 +/- 97 to 77 +/- 62 pg/ml in the CaCO3 group (P < 0.001). Calcium carbonate was also effective in suppressing serum tartrate-resistant acid phosphatase, alkaline phosphatase and intact osteocalcin levels, while calcitriol did not suppress serum osteocalcin. Secretion of interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha) by phytohaemagglutinin A (PHA)-activated peripheral blood mononuclear cells (PBMC) was greater in uraemic patients than in age-matched healthy controls (n = 8). Calcitriol was effective in suppressing secretion of both cytokines, while calcium carbonate was capable of suppressing only TNF-alpha secretion. CCr decreased from 37.4 +/- 15.4 to 33.0 +/- 11.8 ml/min (P < 0.05) in the CaCO3 group, while it did not decrease in either the calcitriol group or the control uraemic group during a 6 month period. These results suggest that supplementation with calcitriol is necessary to maintain bone formation and normalize IL-1 beta and TNF-alpha secretion by activated PBMC in uraemic patients.