부산대학교 도서관

The agent 1,25‐dihydroxy vitamin D3(D3) induces the differentiation of HL‐60 human leukemia cells into functional monocyte‐like cells that can support the intracellular multiplication of Legionella pneumophila.22‐Oxacalcitriol (OCT), a synthetic analogue of D3, ex hibits greater differentiation‐inducing activity than D3in WEHI‐3 mouse leukemia cells and has been suggested to be clinically more useful because of its lower hypercalcemic activity. The abilities of OCT and D3to induce the functional differentiation of human leukemia HL‐60 cells have now been investigated. OCT induced the differentiation of HL‐60 cells into monocyte‐like cells to a similar extent as D3. Thus, both OCT and D3increased (1) the surface expression of CD11b, CD11c, CD14, and CD35; (2) nonspecific esterase staining; and (3) phagocytic ac tivity toward fluorescent beads. HL‐60 cells differentiated in response to OCT also supported the intracellular mul tiplication of L. pneumophila.Activation of both OCT‐and D3‐treated HL‐60 cells with human recombinant interferon‐γ (IFN‐γ) for 24 h before infection markedly inhibited L. pneumophilamultiplication. IFN‐γ activation enhanced superoxide anion generation by D3‐treated HL‐60 cells but not by OCT‐treated HL‐60 cells, suggesting that the inhibition of L. pneumophilamultiplication in IFN‐γ‐activated cells is independent of superoxide generation. Finally, D3, but not OCT, markedly stimu lated the formation of osteoclast‐like multinudeated cells from mouse bone marrow cells, consistent with the lower hypercalcemic activity of OCT. J. Leukoc. Biol.57: 574–580; 1995.