title: Retinoids induce U937 cells to express macrophage phenotype.
abstract: The effects of two retinoids, all-trans-retinoic acid (t-RA) and 13-cis-retinoic acid (c-RA) were studied in a model of osteoclast precursors. The model employs the U937 cell line induced to differentiate when incubated with 1 alpha,25-dihydroxyvitamin D3 and conditioned medium from stimulated human lymphocytes. t-RA and c-RA (10(-8) to 10(-6) M) inhibited cellular growth rates and increased surface adherence. However, t-RA and c-RA both partially blocked the differentiation induced by 1,25(OH)2D3 and lymphokines. Thus, retinoids alone promoted the differentiation of U937 cells but partially blocked the differentiation induced by a vitamin D metabolite and lymphokines. These results suggest that vitamins A and D may exert antagonistic effects on the recruitment of osteoclast precursors.
mesh_terms: D000954:Antigens, Surface / Q000032:analysis; D002117:Calcitriol / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006801:Humans; D008222:Lymphokines / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects*; D009000:Monocytes / Q000187:drug effects*; D010641:Phenotype; D013237:Stereoisomerism; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D000954:Antigens, Surface; D008222:Lymphokines; D014212:Tretinoin; D002117:Calcitriol