title: Independent regulation of human neutrophil chemotactic receptors after activation.
abstract: The fluoresceinated chemotactic factors, C5a, formyl-methionyl-leucyl-phenylalanyl-lysine (FMLPL), and casein were used in conjunction with flow cytometry to examine chemotactic factor receptor expression on polymorphonuclear leukocytes (PMN) activated with phorbol myristate acetate (PMA), C5a, or formyl-methionyl-leucyl-phenylalanine. Activation with PMA resulted in a dose-dependent increase in binding of fluorescein-labeled (FL)-casein and (FL-FMLPL) over the range of PMA concentrations from 0.5 to 50 ng/ml. In contrast, activation of PMN with PMA resulted in a dose-dependent decrease in FL-C5a binding, and activation with concentrations above 5 ng/ml resulted in a complete loss of binding. This loss of binding was not caused by inactivation of the ligand or prevented by the addition of superoxide dismutase and catalase or protease inhibitors. Furthermore, incubation of PMN with supernatants from PMN stimulated to degranulate did not reduce the availability of C5a receptors. This pattern of increased FMLPL and casein binding with decreased C5a binding was also observed with cytochalasin B-pretreated PMN that were stimulated with chemotactic factors. Parallel studies of superoxide anion generation demonstrated that PMA-treated PMN were still responsive to formyl-methionyl-leucyl-phenylalanine, but not to C5a. These data demonstrate that the activation of PMN up-regulates formyl peptide and casein receptors whereas C5a receptors are down-regulated under similar conditions.
authors.affiliation: Department of Pathology, University of New Mexico, School of Medicine, Albuquerque 87131.
authors.forename: J G
authors.initials: JG
authors.lastname: Bender
authors.forename: D E
authors.initials: DE
authors.lastname: Van Epps
authors.forename: D E
authors.initials: DE
authors.lastname: Chenoweth
mesh_terms: D002364:Caseins / Q000378:metabolism; D002634:Chemotaxis, Leukocyte; D003182:Complement C5 / Q000378:metabolism; D015936:Complement C5a; D003571:Cytochalasin B / Q000494:pharmacology; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism; D009504:Neutrophils / Q000502:physiology*; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement / Q000502:physiology*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D002364:Caseins; D003182:Complement C5; D005456:Fluorescent Dyes; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D013481:Superoxides; D003571:Cytochalasin B; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D013755:Tetradecanoylphorbol Acetate