Vitamin D3 compounds regulate human immunodeficiency virus type 1 replication in U937 monoblastoid cells and in monocyte-derived macrophages

We studied the effects of vitamin D3 compounds on the replication of human immunodeficiency virus type 1 (HIV-1) in the monoblastoid cell line U937 and in primary monocyte-derived macrophage cultures to understand how modulators of monocyte/macrophage effector function might affect the pathogenesis of HIV-1 infection. U937 cell cultures exposed to 1, alpha 25-dihydroxyvitamin D3 prior to HIV-1 infection showed enhanced virus replication that was apparently due to increased cellular resistance to viral cytopathic effects; a marked inhibition of virus replication was noted in cells exposed to 1 alpha,25-dihydroxyvitamin D3 subsequent to infection. Exposure of blood-derived monocyte/macrophages to vitamin D3 compounds prior to infection also affected virus growth; in most cases, substantial inhibition of HIV-1 replication was noted in vitamin D3-treated macrophage cultures. Our results demonstrate that vitamin D3 compounds with recognized abilities to induce cellular differentiation can modulate HIV-1 infection of human macrophages.