VITAMIN-D RECEPTOR QUANTITATION IN HUMAN BLOOD MONONUCLEAR-CELLS IN HEALTH AND DISEASE

Vitamin D receptor (VDR) concentration was quantitated in human periph eral blood mononuclear cells (PBMC) from patients with absorptive hype rcalciuria (AH) and patients with high 1,25(OH)2D3 due to acquired or transient disease states and the results compared to those in normal s ubjects. VDR concentration in resting cells was not different between the three groups and represented constitutive receptor expression of m onocytes. Following activation with phytohemagglutinin, patients with hypercalcitriolemia demonstrated significantly greater VDR concentrati ons. Patients with AH demonstrated a normal value for the group, but 6 patients had significantly greater concentrations of VDR despite norm al plasma 1,25(OH)2D3 in four of the patients. Proliferation, as asses sed from [H-3]thymidine incorporation was inversely correlated with se rum 1,25(OH)2D3 and was significant (R = - 0.299, p = 0.048). Taken to gether, the results suggest that PBMC provide a useful system for stud ying VDR status in transient or acquired states of hypercalcitriolemia . Furthermore, the studies in patients with absorptive hypercalciuria disclosed it to be a heterogenous disorder, characterized by both vita min D-dependent and D-independent forms of receptor up-regulation.