title: CD4 on CD8(+) T cells directly enhances effector function and is a target for HIV infection.
abstract: Costimulation of purified CD8(+) T lymphocytes induces de novo expression of CD4, suggesting a previously unrecognized function for this molecule in the immune response. Here, we report that the CD4 molecule plays a direct role in CD8(+) T cell function by modulating expression of IFN-gamma and Fas ligand, two important CD8(+) T cell effector molecules. CD4 expression also allows infection of CD8 cells by HIV, which results in down-regulation of the CD4 molecule and impairs the induction of IFN-gamma, Fas ligand, and the cytotoxic responses of activated CD8(+) T cells. Thus, the CD4 molecule plays a direct role in CD8 T cell function, and infection of these cells by HIV provides an additional reservoir for the virus and also may contribute to the immunodeficiency seen in HIV disease.
authors.affiliation: Department of Medicine and Microbiology, David Geffen School of Medicine, University of California, 11-934 Factor Building, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.
authors.forename: Scott G
authors.initials: SG
authors.lastname: Kitchen
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Jones
authors.forename: Stuart
authors.initials: S
authors.lastname: LaForge
authors.forename: Jason K
authors.initials: JK
authors.lastname: Whitmire
authors.forename: Bien-Aimee
authors.initials: BA
authors.lastname: Vu
authors.forename: Zoran
authors.initials: Z
authors.lastname: Galic
authors.forename: David G
authors.initials: DG
authors.lastname: Brooks
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Brown
authors.forename: Christina M R
authors.initials: CM
authors.lastname: Kitchen
authors.forename: Jerome A
authors.initials: JA
authors.lastname: Zack
mesh_terms: D015704:CD4 Antigens / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D053222:Fas Ligand Protein; D015658:HIV Infections / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D018448:Models, Immunological; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D015704:CD4 Antigens; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D007371:Interferon-gamma