title: Close co-localization of CD4 and a serine esterase tryptase TL2 on the cell-surface of human monocytoid and CD4+ lymphoid cells.
abstract: Tryptase TL2, a serine esterase in the membrane of human monocytoid and CD4+ lymphoid cells, specifically binds to the V3 domain of HIV-1 gp120. Here we report that monoclonal antibodies against CD4 that recognize the epitope interacting with gp120 specifically blocked the immunostaining of cell-surface tryptase TL2, although the antibody does not cross-react with tryptase TL2. Down-regulation of cell-surface CD4 induced by HIV-1 Nef prevented this blocking effect. These data suggest that CD4 is closely co-localized with tryptase TL2 on the cell surface and that regulation of the expression of tryptase TL2 is not associated with that of CD4.
authors.affiliation: Department of Parasitology, Kurume University School of Medicine, Fukuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Hoshino
authors.forename: T
authors.initials: T
authors.lastname: Fukuma
authors.forename: Y
authors.initials: Y
authors.lastname: Niwa
authors.forename: H
authors.initials: H
authors.lastname: Kido
mesh_terms: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure; D015536:Down-Regulation; D006801:Humans; D046911:Macromolecular Substances; D009000:Monocytes / Q000648:ultrastructure*; D012697:Serine Endopeptidases / Q000378:metabolism*; D053802:Tryptases
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D046911:Macromolecular Substances; D012697:Serine Endopeptidases; D053802:Tryptases; C070201:tryptase TL(2)