LYMPHOCYTE CELL-LINES FROM VITAMIN-D-DEPENDENT RICKETS TYPE-II SHOW FUNCTIONAL DEFECTS IN THE 1-ALPHA,25-DIHYDROXYVITAMIN-D3 RECEPTOR

Lymphocyte cell lines were established from five patients with vitamin D-dependent rickets, type II (VDDR-II). These Unes were established by infection with human T-lymphotrophic virus type I (HTLV-I). Binding of [3H]1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) to its receptor in these cell lines was compared to binding studies using a T-lymphocyte cell line (S-LB1) from a normal individual. The 1,25(OH)2D3 receptor of S-LB1 was comparable to the well-characterized chick intestinal 1,25(OH)2D3 receptor in terms of its ligand binding affinity and capacity, its mobility on 5-20% sucrose gradients, and its adsorption to and elution properties from DNA-cellulose. Three cell Unes estabUshed from patients with VDDR-II (Rh-VDR, Sh-VDR, and Ab-VDR) showed no specific binding of 1,25(OH)2D3 to a receptor and treatment of the cultured cells with 1,25(OH)2D3 did not stimulate production of 24,25-dihydroxy-vitamin D3 (24,25(OH)2D3), a response which is diagnostic of the presence of a functional 1,25(OH)2D3 receptor. In a fourth cell line, Al-VDR, the receptor for 1,25(OH)3D3 had a low binding capacity and 25(OH)D3-24-hydroxylase activity was not detectable. Induction of 24,25-(OH)2D3 synthesis by l,25(OH)2D3was observed in the fifth cell Une, designated Ro-VDR, although the sensitivity to hormone treatment was lower than in the control cell Une from a normal donor. The capacity of the receptor for 1,25(OH)2D3 was low in Ro-VDR. In all cell Unes where 1,25(OH)2D3 binding to a receptor was detectable, the receptor had the typical sedimentation coefficient of 3.7 S on sucrose density gradient analysis. Binding and elution properties to DNA-cellulose, however, differed from normal in both Ro-VDR and Al-VDR cells where elution from DNA-cellulose occurred at at lower salt concentration than is typical of the 1,25(OH)2D3 receptor. While Ro-VDR cells showed typical nuclear localization of the unoccupied 1,25(OH)2D3 receptor, neither the unoccupied nor the occupied receptor from Al-VDR cells was completely localized in the nucleus. © 1990.