title: Transpleural gradient of 1,25-dihydroxyvitamin D in tuberculous pleuritis.
abstract: We used tuberculous pleuritis as a model to study the compartmentalization and potential immunoregulatory role of 1,25-dihydroxyvitamin D [1,25-(OH)2-D] in human granulomatous disease. In tuberculous pleuritis, mean concentrations of total 1,25-(OH)2-D were elevated in pleural fluid, compared to blood (67 pg/ml vs. 35 pg/ml). Concentrations of albumin, protein and 25-hydroxyvitamin D (25-OH-D) were lower in pleural fluid than blood, suggesting that accumulation of binding proteins does not explain the transpleural gradient of 1,25-(OH)2-D. The mean free 1,25-(OH)2-D concentration in pleural fluid was increased 5.3-fold over that in serum. 1,25-(OH)2-D3 inhibited PPD-induced proliferation of pleural fluid mononuclear cells, antigen-reactive lines and T lymphocyte clones derived from a single cell. Patient-derived PPD-reactive lines expressed a high-affinity intracellular binding moiety for 1,25-(OH)2-D3. Pleural fluid mononuclear cells and PPD-reactive lines did not metabolize 25-OH-D3 to 1,25-(OH)2-D3. The sum of these data suggests that concentration of 1,25-(OH)2-D in pleural fluid of tuberculosis patients is probably due to local hormone production by pleural tissue-based inflammatory cells that are not present in significant numbers in pleural fluid. Elevated concentrations of 1,25-(OH)2-D in pleural fluid may exert receptor-mediated inhibition of antigen-induced proliferation by pleural fluid lymphocytes. Inhibition of lymphocyte proliferation and lymphokine production may prevent tissue destruction from an uncontrolled inflammatory response.
authors.affiliation: Department of Medicine, University of Southern California School of Medicine, Los Angeles 90033.
authors.forename: P F
authors.initials: PF
authors.lastname: Barnes
authors.forename: R L
authors.initials: RL
authors.lastname: Modlin
authors.forename: D D
authors.initials: DD
authors.lastname: Bikle
authors.forename: J S
authors.initials: JS
authors.lastname: Adams
mesh_terms: D002117:Calcitriol / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D010996:Pleural Effusion / Q000378:metabolism*; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014373:Tuberculin / Q000276:immunology; D014396:Tuberculosis, Pleural / Q000276:immunology / Q000378:metabolism*
chemical_list: D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D014373:Tuberculin; D002117:Calcitriol