Human cord blood mononuclear cells are preferentially infected by non- syncytium-inducing, macrophage-tropic human immunodeficiency virus type 1 isolates

Abstract

Identification of the factors which impact on the transmission of human immunodeficiency virus type 1 (HIV-1) from an infected mother to her infant is essential for the development of effective strategies to prevent perinatal HIV-1 infection. The current study was designed to determine if unstimulated human neonatal cord blood mononuclear cells (CBMC) differ from adult peripheral blood mononuclear cells (PBMC) in susceptibility to HIV-1 infection. Both cell populations were challenged with two laboratory and two clinical HIV-1 isolates with different phenotypic properties. Infection was evaluated by quantitation of p24 antigen production and p24 antigen expression by an enzyme immunoassay and immunofluorescence, respectively. T- cell markers were determined by flow cytometry. Unstimulated CBMC were preferentially infected by macrophagetropic, non-syncytium-inducing (non-SI) laboratory and clinical isolates, whereas PBMC were more susceptible to T- lymphotropic, SI HIV-1 strains. The macrophage-tropic strain HIV-1(Ba-1) replicated to 100-fold higher titers in CBMC than a similar inoculum of the St isolate HIV-1(LA1). The opposite occurred in unstimulated PBMC, which replicated HIV(LA1) to eightfold higher liters than the macrophage-tropic isolate. These findings indicate that a selection of viral phenotype may occur with unstimulated CBMC displaying a predominant susceptibility to infection by macrophage-tropic, non-SI HIV-1 strains and thai this selection may influence mother-infant transmission of HIV-1.