PMN Plasma Membrane Research Articles

Role of Microtubules in Granulocyte Adherence

Abstract The adherence of human polymorphonuclear leukocytes (PMN) to nylon fibers is inhibited in a dose-dependent fashion by exposure in vitro of these cells to either colchicine or VM-26, both of which agents prevent microtubule assembly. Mean adherence of human PMN was 48% +/- 2%, following treatment with 10(-5) M colchicine or 10(-4) M VM-26 it was reduced to 31% +/- 2% and 7%, respectively. Peritoneal PMN obtained from mice and mink with Chediak-Higashi syndrome (CHS) thought to have a microtubule-membrane disorder affecting the PMN had a mean adherence of 29% +/- 3% and 40% +/- 8% compared to control values of 46% +/- 5% and 73% +/- 8%, respectively, from the mice and mink. Both ascorbic acid and bethanechol, shown previously to enhance microtubule assembly in humans with CHS, normalized granulocyte adherence in PMN obtained from mice with CHS. Cyclic nucleotide levels were not altered by treatment of human PMN with colchicine, nor did they differ between normal and CHS animals. Thus it appears that the state of microtubule assembly may directly affect the properties of the PMN plasma membrane without requiring alterations of cyclic nucleotides as an intermediary.

Transport of sodium, potassium, and calcium across rabbit polymorphonuclear leukocyte membranes. Effect of chemotactic factor.

The transport properties of the rabbit peritoneal polymorphonuclear leukocyte (PMN) plasma membrane to Na+, K+, and Ca2+ have been characterized. The use of a silicone oil centrifugation technique provided a rapid and reliable method for measuring ion fluxes in these cells. Na+ and K+ movements across PMN membranes were found to be rapid. The value for the unifirectional steady-state fluxes (in meq/liter cell X min) were of the order of 3.0 for Na+ and 7.4 for K+. Ouabian inhibited both K+ influx and Na+ efflux, the latter being also dependent on the presence of extracellular potassium. The rate constant (in min-1) for 45Ca influx was found to be .05 and that for 45Ca efflux .04. The synthetic chemotactic factor formyl-methionyl-leucyl-phenylalanine (FMLP) was found to affect the fluxes of Na+, K+, and Ca2+ at concentrations as low as 10(-10)M. FMLP induced a large and rapid increase in the permeability of the PMN plasma membrane to 22Na. Smaller and delayed enhancements of 42K influx and 22Na efflux were also noted. Some evidence that the latter findings are a consequence of the increased 22Na influx is presented. 45Ca influx and efflux were also stimulated by FMLP. In the presence of 0.25 mM extracellular calcium, FMLP induced an increase in the steady-state level of cell-associated 45Ca. In the presence of .01 mM extracellular calcium, however, a transient decrease in the steady-state level of cell-associated 45Ca was induced by FMLP. The curves relating the concentration of FMLP to its effects on cation fluxes are very similar to those found for its enhancement of migration.

Lysosomal Enzyme Release from Human Leukocytes: Mediation by the Alternate Pathway of Complement Activation

Abstract In “Lysosomal Enzyme Release from Human Leukocytes: Mediation by the Alternate Pathway of Complement Activation” by Ira M. Goldstein, Melchiorre Brai, Abraham G. Osler, and Gerald Weissmann in the July 1973 issue of the Journal of Immunology, Volume 111, Number 1, page 33, beginning with the last sentence the abstract should read as follows: “Levels of C3 proactivator in treated sera correlated inversely with enzyme releasing activity. These data suggest that complement interacts with and perturbs the PMN plasma membrane sufficiently to cause lysosomal membrane perturbation, fusion, and ultimately lysosomal enzyme extrusion by a process of ‘reverse endocytosis’.”

Lysosomal Enzyme Release from Human Leukocytes: Mediation by the Alternate Pathway of Complement Activation

Abstract The alternate pathway of complement activation has recently assumed an important role in the mediation of inflammation and tissue injury. We have found that complement activated via this pathway interacts with human polymorphonuclear leukocytes (PMN) in the absence of particulates and stimulates the selective release of lysosomal enzymes. Fresh human serum, after treatment with zymosan or cobra venom factor, yields a fluid phase component which induces cytochalasin B-treated PMN to release β-glucuronidase without leakage of cytoplasmic lactate dehydrogenase. Involvement of the alternate pathway of complement activation is evidenced by failure of serum to yield enzyme-releasing activity after pretreatment with rabbit antihuman C3 proactivator, 0.01 M EDTA but not 0.01 M EDTA, 0.02 M salicylaldoxime, 0.02 M hydrazine or by heating to 56°C for 30 min. Levels of C3 proactivator in treated sera correlated inversely with and perturbs the PMN plasma membrane sufficiently to cause lysosomal membrane perturbation, fusion, and ultimately lysosomal enzyme extrusion by a process of “reverse endocytosis.”