Human herpesvirus-6-associated suppression of growth factor-induced macrophage maturation in human bone marrow cultures

Abstract

Abstract Cultures of marrow mononuclear cells were exposed to medium derived from cell cultures infected with several different strains of human herpesvirus-6 (HHV-6) immediately before the addition of either of two growth factors, granulocyte-macrophage colony-stimulating factor and interleukin-3. Exposure to any of the viral preparations suppressed the outgrowth of nonspecific esterase-positive adherent macrophages induced by the factors by more than 90%. The nonadherent cell populations in the infected cultures were numerically similar to those in uninfected control cultures, demonstrating the absence of a nonspecific cytotoxic effect of the viral materials. Infectious virus was not necessary for the macrophage outgrowth suppression. These findings suggest that HHV-6 either encodes or induces a soluble mediator or mediators that can interfere with the responses of bone marrow to growth factors and possibly block the normal differentiation of macrophages from marrow precursors.