title: The role of transmembrane cationic gradients in immune complex stimulation of human polymorphonuclear leukocytes.
abstract: The role of monovalent cationic gradients in human polymorphonuclear leukocyte (PMNL) stimulation was investigated by monitoring immune complex-stimulated transmembrane depolarization and superoxide production, events which accompany--and have been used as indicators of --PMNL activation. Abolishing only the Na+ gradient by substitution of choline for extracellular Na+ did not affect the resting membrane potential but reduced the rate of stimulus-induced transmembrane depolarization to 50% of control. In contrast, collapsing both Na+ and K+ gradients by suspension in K+ buffer (high K-PRK) depolarized the cells and reduced the stimulus-induced rate of depolarization to 11% of control. Pretreatment of cells suspended in Na+ buffers with 5-(N,N-dimethyl)amiloride hydrochloride (DMA) or with valinomycin reduced by one-half the rate of immune complex induced membrane depolarization. Conversely, in the absence of either or of both Na+ or K+ gradients, or in the presence of valinomycin, immune complex elicited an enhanced rate of superoxide production. However, PMNL prepared via NH4Cl (NH4Cl-PMNL) instead of H2O (H2O-PMNL) lysis of residual red blood cells exhibited an absolute requirement for an intact Na+ gradient in cell stimulation. The present results thus demonstrate that: 1) both Na+ and K+ gradients participate equally in the membrane depolarization elicited by immune complex; 2) neither a Na+ or a K+ gradient is required for immune complex activation, or for activity of the respiratory burst; and 3) an artifactual requirement for an intact Na+ gradient occurs in neutrophils prepared by the NH4Cl lysis technique.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118.
authors.forename: F W
authors.initials: FW
authors.lastname: Luscinskas
authors.forename: D E
authors.initials: DE
authors.lastname: Mark
authors.forename: B
authors.initials: B
authors.lastname: Brunkhorst
authors.forename: F J
authors.initials: FJ
authors.lastname: Lionetti
authors.forename: E J
authors.initials: EJ
authors.lastname: Cragoe
authors.forename: E R
authors.initials: ER
authors.lastname: Simons
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology; D000936:Antigen-Antibody Complex / Q000502:physiology*; D002414:Cations, Monovalent / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003584:Cytological Techniques; D004594:Electrophysiology; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation; D009504:Neutrophils / Q000378:metabolism / Q000502:physiology*; D010101:Oxygen Consumption; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D014867:Water / Q000494:pharmacology
chemical_list: D000936:Antigen-Antibody Complex; D002414:Cations, Monovalent; D000643:Ammonium Chloride; D014867:Water; D012964:Sodium; D011188:Potassium