Agonist-stimulated Cl- efflux from human neutrophils. A common phenomenon during neutrophil activation.
When human peripheral blood neutrophils were stimulated with various agonists which activate and/or prime neutrophils, we found that Cl- efflux was enhanced with a dramatic (50%) loss of intracellular Cl-. Interestingly, the Cl- efflux was enhanced by both agonists which induce a rapid transient increase in intracellular Ca2+ concentration ([Ca2+]i) [class I, e.g. N-formyl-methionyl-leucyl-phenylalanine (fMLP), interleukin-8 (IL8), platelet-activating factor, leukotriene B4 and C5a] and those which do not induce such an [Ca2+]i elevation [class II, e.g. tumor necrosis factor alpha (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF)]. The time course of agonist-stimulated Cl- efflux differed depending on the agonist. Class I agonists such as IL8 and fMLP exhibited a 1 min lag phase before the onset of Cl- efflux; class II agonists such as GM-CSF and TNF displayed a 2 and 5 min lag phase, respectively. Both IL8 (class I)- and TNF (class II)-stimulated Cl- efflux exhibited similar sensitivity to inhibition by different types of ion transport inhibitors [ethacrynic acid (EA), amiloride, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid, anthracene-9-carboxylic acid, and 4-4'-diisothiocyanatostilbene-2,2'-disulfonic acid]. On the other hand, natural Cl- efflux, which is thought to be mainly mediated by Cl-/Cl- self exchange, was not inhibited by EA (0.5 mM) or amiloride (0.3 mM). These results imply that both class I and class II agonist-stimulated Cl- efflux occurs via a common Cl- transporter which is different from that reported previously in resting human neutrophils. Although all agonists which induced a Cl- efflux also induced shape change of neutrophils, there did not appear to be a causal relationship between shape change and agonist-stimulated Cl- efflux. However, a temporal correlation was found to exist between agonist-stimulated Cl- efflux and intracellular alkalinization following agonist stimulation. Agonist-stimulated Cl- efflux therefore seems to be a common phenomenon activated by several agonists which act through different signal transduction pathways.
Yamanouchi Research Institute, Littlemore Hospital, Oxford, U.K.
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Y
Shimizu
R H
RH
Daniels
M A
MA
Elmore
M J
MJ
Finnen
M E
ME
Hill
J M
JM
Lackie
D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D015936:Complement C5a / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016209:Interleukin-8 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D002712:Chlorides; D016209:Interleukin-8; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D002118:Calcium