title: Elevated 1- α hydroxylase activity in monocytes from patients with active tuberculosis.
abstract: A uremic patient developed hypercalcemia after tuberculosis infection, and his ionized calcium levels correlated with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) levels. We performed further studies to determine whether monocytes are alternative sites of 1,25(OH)2D3 conversion beyond renal tubular cells. Using an ex vivo bioassay, in this study, we found that 1- α hydroxylase (CYP27B1) activity in monocytes is significantly higher in patients with active tuberculosis (TB) than in those with frequent TB contact. However, when monocytes from patients with active TB were restimulated with antigen derived from Mycobacterium tuberculosis, less 1,25(OH)2D3 was observed. In contrast, the level of 1,25(OH)2D3 was unchanged in those with frequent TB contact. We conclude that monocytes may be an alternative source of 1- α hydroxylase that could convert 25-hydroxyvitamin D3 to the more active 1,25(OH)2D3.
authors.affiliation: Department of Public Health and Environmental Medicine, College of Medicine, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan ; Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan ; School of Medicine, College of Medicine, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan.
authors.forename: Yi-Ching
authors.initials: YC
authors.lastname: Tung
authors.affiliation: Department of Internal Medicine, Kaohsiung Medical University Hospital, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan.
authors.forename: Tsan-Teng
authors.initials: TT
authors.lastname: Ou
authors.affiliation: School of Medicine, College of Medicine, Kaohsiung Medical University, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan ; Department of Internal Medicine, Kaohsiung Medical University Hospital, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan ; Laboratory Medicine, Kaohsiung Medical University Hospital, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan.
authors.forename: Wen-Chan
authors.initials: WC
authors.lastname: Tsai
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000378:metabolism*; D000328:Adult; D002118:Calcium / Q000097:blood / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000201:enzymology* / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology* / Q000378:metabolism*; D014511:Uremia / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism
chemical_list: C118756:dihydroxy-vitamin D3; D014807:Vitamin D; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D002118:Calcium