title: CXCR-4 is expressed by primary macrophages and supports CCR5-independent infection by dual-tropic but not T-tropic isolates of human immunodeficiency virus type 1.
abstract: Primary macrophages are infected by macrophage (M)-tropic but not T-cell line (T)-tropic human immunodeficiency virus type 1 (HIV-1) strains, and CCR5 and CXCR-4 are the principal cofactors utilized for CD4-mediated entry by M-tropic and T-tropic isolates, respectively. Macrophages from individuals homozygous for an inactivating mutation of CCR5 are resistant to prototype M-tropic strains that depend on CCR5 but are permissive for a dual-tropic isolate, 89.6, that can use both CCR5 and CXCR-4, as well as CCR2b, CCR3, and CCR8. Here we show that 89.6 entry into CCR5-deficient macrophages is blocked by an anti-CXCR-4 antibody and by the CXCR-4-specific chemokine SDF but not by the ligands to CCR2b or CCR3. Reverse transcription-PCR demonstrated expression of CXCR-4 but not CCR3 or CCR8 in macrophages, while CCR2b was variable. Macrophage surface expression of CXCR-4 was confirmed by immunofluorescence staining and flow cytometry. Thus, CXCR-4 is expressed by primary macrophages and functions as a cofactor for entry by dual-tropic but not T-tropic HIV-1 isolates, and macrophage resistance to T-tropic strains does not result from a lack of the T-tropic entry cofactor CXCR-4. Since CXCR-4 on macrophages can be used by some but not other isolates, these results indicate that HIV-1 strains differ in how they utilize chemokine receptors as cofactors for entry and that the ability of a chemokine receptor to mediate HIV-1 entry differs, depending on the cell type in which it is expressed.
authors.affiliation: Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Yi
authors.forename: S
authors.initials: S
authors.lastname: Rana
authors.forename: J D
authors.initials: JD
authors.lastname: Turner
authors.forename: N
authors.initials: N
authors.lastname: Gaddis
authors.forename: R G
authors.initials: RG
authors.lastname: Collman
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D015497:HIV-1 / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D006801:Humans; D008264:Macrophages / Q000502:physiology* / Q000821:virology*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D019713:Receptors, CCR5 / Q000235:genetics / Q000502:physiology*; D019718:Receptors, CXCR4 / Q000235:genetics / Q000502:physiology*; D013601:T-Lymphocytes / Q000821:virology; D014779:Virus Replication
chemical_list: D017931:DNA Primers; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; D012313:RNA