title: Expression and function of chemokine receptors on human thymocytes: implications for infection by human immunodeficiency virus type 1.
abstract: The presence or absence of the receptor CD4 and the coreceptors CCR5 and CXCR4 restrict the cell tropism of human immunodeficiency virus type 1 (HIV-1). Despite the importance of thymic infection by HIV-1, conflicting reports regarding the expression of HIV-1 coreceptors on human thymocytes have not been resolved. We assayed the expression and function of the major HIV-1 coreceptors, CCR5 and CXCR4, as well as CCR4 and CCR7 as controls, on human thymocytes. We detected CCR5 on 2.5% of thymocytes, CXCR4 on 53% of the cells, and CCR4 on 16% and CCR7 on 11% of human thymocytes. Moreover, infection by R5 HIV-1 did not significantly induce expression of CCR5. We found that two widely used anti-CCR5 monoclonal antibodies cross-reacted with CCR8, which may account for discrepancies among published reports of CCR5 expression on primary cells. This cross-reactivity could be eliminated by deletion of amino acids 2 through 4 of CCR8. Chemotaxis assays showed that SDF-1, which binds CXCR4; MDC, which binds CCR4; and ELC, which binds CCR7, mediated significant chemotaxis of thymocytes. In contrast, MIP-1beta, whose receptor is CCR5, did not induce significant chemotaxis. Our results indicate that CXCR4, CCR4, CCR7, and their chemokine ligands may be involved in thymocyte migration during development in the thymus. CCR5 and its ligands, however, are likely not involved in these processes. Furthermore, the pattern of CCR5 and CXCR4 expression that we found may explain the greater susceptibility of human thymocytes to infection by HIV-1 isolates capable of using CXCR4 in cell entry compared to those that use only CCR5.
authors.affiliation: Department of Microbiology and Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, Virginia 22908, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Taylor
authors.forename: K C
authors.initials: KC
authors.lastname: Kimbrell
authors.forename: R
authors.initials: R
authors.lastname: Scoggins
authors.forename: M
authors.initials: M
authors.lastname: Delaney
authors.forename: L
authors.initials: L
authors.lastname: Wu
authors.forename: D
authors.initials: D
authors.lastname: Camerini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D054415:Chemokine CCL19; D054422:Chemokine CCL22; D054407:Chemokine CCL4; D054377:Chemokine CXCL12; D019742:Chemokines, CC / Q000378:metabolism; D019743:Chemokines, CXC / Q000378:metabolism; D002633:Chemotaxis / Q000502:physiology; D003429:Cross Reactions; D004195:Disease Models, Animal; D015658:HIV Infections / Q000378:metabolism* / Q000821:virology; D015497:HIV-1 / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D008969:Molecular Sequence Data; D054398:Receptors, CCR4; D019713:Receptors, CCR5 / Q000096:biosynthesis / Q000276:immunology; D054400:Receptors, CCR7; D054401:Receptors, CCR8; D019718:Receptors, CXCR4 / Q000096:biosynthesis; D019707:Receptors, Chemokine / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; C515460:CCL19 protein, human; C515482:CCL22 protein, human; C515354:CCR4 protein, human; C515370:CCR7 protein, human; C103330:CCR8 protein, human; C515255:CXCL12 protein, human; C515461:Ccl19 protein, mouse; C515483:Ccl22 protein, mouse; C515355:Ccr4 protein, mouse; C515371:Ccr7 protein, mouse; D054415:Chemokine CCL19; D054422:Chemokine CCL22; D054407:Chemokine CCL4; D054377:Chemokine CXCL12; D019742:Chemokines, CC; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D019402:Macrophage Inflammatory Proteins; D054398:Receptors, CCR4; D019713:Receptors, CCR5; D054400:Receptors, CCR7; D054401:Receptors, CCR8; D019718:Receptors, CXCR4; D019707:Receptors, Chemokine