Calcitriol reduces the occurrence of acute cellular rejection of liver transplants: a prospective controlled study

To investigate the acute cellular rejection rate of liver transplant recipients taking or not taking calcitriol in a prospective, randomized, controlled clinical study.

Primary liver transplant patients were randomized to receive the placebo (arm A), calcium gluconate (arm B) or calcium gluconate plus calcitriol (arm C). The composition of circulating T cell subpopulations was determined by flow cytometry at baseline and one week post transplant. The primary endpoint was acute cellular rejection rate at one month post transplant.

Seventy-five liver transplant recipients were eligible, including 25 patients each in arm A, B and arm C. The mean baseline serum 25-(OH) vitamin D content was 12.5 +/- 3.0 (range, 2.5 to 19.5) ng/mL, with no statistical difference among the three arms. Among 7 (9.33%) patients who developed definite acute cellular rejection (Banff score > or = 6), only 1 (4%, 1/25) were from arm C while 6 (12%, 6/50) of them were from either arm A or B. The acute cellular rejection rate was 20% (5/25) for arm C, 32% (8/25) for arm A and 28% (7/25) for arm B (arm C vs. arm A or B, P < 0.05). Flow cytometric analysis showed that the proportion of circulating CD4+ CD25(high) CD(127-)(Treg) cells in arm C increased by 63.22% at one week post transplant (3.95 +/- 4.0%) compared to baseline (2.42 +/- 2.35%) (P < 0.05). No significant difference was observed in arm A or B (P > 0.05 in both vs. baseline). Furthermore, no significant difference was noted among the three arms in the proportion of CD4(+)CD45RA(-)CD45RO(+), CD4(+)CD25(low)CD45RA(+) and CD4(+)CD25(low)CD45RA(-) T cells at one week post transplant compared to baseline.

Calcitriol has apparent beneficial effect on acute cellular rejection of liver transplants, which may be associated with increases in the proportion of circulating Treg cells.