Volume changes in activated human neutrophils: The role of Na⁺/H⁺ exchange

Abstract

The apparent volume of neutrophils, as measured electronically with the Coulter counter, has been reported to increase upon treatment with chemotactic factors. The occurrence of a volume change was confirmed by forward angle light scattering and by isotopic measurements of intracellular water space in cells treated with 12-O-tetradecanoylphorbol 13,acetate (TPA) or formyl-methionyl-leucyl-phenylalanine (FMLP). Cell swelling was associated with an increase in the osmotic content of the cells, determined from Boyle-van't Hoff plots, and with an increase in Na+ content, measured by flame photometry. The volume change was inhibited by replacement of extracellular Na+ with K+ or N-methyl-D-glucamine+, or by addition of amiloride. Swelling was also inhibited by the 5-N-substituted analogs of amiloride, which are potent specific inhibitors of the Na+/H+ antiport. This pathway is activated in neutrophils by both TPA and FMLP. Activation of Na+/H+ exchange, determined as a Na+ -dependent and amiloride-sensitive cytoplasmic alkalinization, was also found when neutrophils were treated with hypertonic solutions. The hypertonic activation of the antiport was similarly followed by cell swelling, detectable by electronic sizing. The results indicate that activation of Na+/H+ exchange can lead to significant cell swelling in neutrophils.

High Light Scatter by Neutrophils in the Bayer-Technicon H*2 Analyzer: A Screening Test of Morphologically Defective Responsiveness to in vitro Chemotactic Stimulation

“…Conversely, our volume assay of formyl-methionyl-leucyl-phenylalanine-activated neutrophils, did show a formyl-methionyl-leucyl-phenylalanine Volumetrie rise s an effect of the Stimulation. The same has been shown for polymorphonuclear leukocytes activated in vitro, by our group and by other authors using different Stimuli (8)(9)(10)(11). The causes of in vivo activation, inducing large polymorphonuclear leukocytes with ybar valueŝ 37.00 arbitrary units, may be investigated by analysis of pathogenetic events occurring in patients with high ybar basal values aiid defective or null response to formyl-methionyl-leucyl-phenylalanine.…”

Single‐cell analysis of the intracellular pH and its regulation during the monocytic differentiation of U937 human leukemic cells

“…The higher sensitivity of the Na'/Ht exchange system of leukemic cell lines to amiloride and its derivatives and its lower affinity for alkali cations might be related 171. Another distinct property of leukemic cells is that the N a + / H + exchange system of neutrophils and lymphocytes can be activated by osmotic shocks [23,24], whereas the antiport of U937 and HL60 cells cannot (A. Ladoux and C. Frelin, unpublished results). A second pHi-regulating mechanism in U937 cells is a Na'-dependent HCO,/Cl-exchange system [14].…”

Biochemical, Structural, and Functional Abnormalities of Polymorphonuclear Leukocytes in the Neonate

“…Following ligand-receptor interaction, a complicated series of events occurs that subsequently results in functional activity. These events include changes in membrane potential (2 1-23), the breakdown of phosphoinositol into inositol triphosphate and diacyl-glycerol (24), an increase in free intracellular calcium ion (Ca++) (23,25,26) provoked, in part, by inositol triphosphate, diacyl-glycerol-induced phosphokinase C activation (24), sodium ion (Na+) influx (27), alkalinization of the cytoplasm (28), and an increase in cell volume (27). Although, probably not directly involved in signal transduction of the PMN (29), there is also activation of adenylate cyclase and the generation of a transient elevation in cyclic 3'5' adenosine monophosphate (30, 3 1).…”