IMMUNOELECTRON MICROSCOPY REVEALS SIGNIFICANT GRANULE FUSION UPON STIMULATION OF ELECTROPERMEABILIZED HUMAN NEUTROPHILS

Citation
Hwm. Niessen et al., IMMUNOELECTRON MICROSCOPY REVEALS SIGNIFICANT GRANULE FUSION UPON STIMULATION OF ELECTROPERMEABILIZED HUMAN NEUTROPHILS, Cellular signalling, 6(1), 1994, pp. 47-58
Citations number
17
Categorie Soggetti
Biology
Journal title
ISSN journal
08986568
Volume
6
Issue
1
Year of publication
1994
Pages
47 - 58
Database
ISI
SICI code
0898-6568(1994)6:1<47:IMRSGF>2.0.ZU;2-H
Abstract
Although electropermeabilization has become an important tool for stud ying the signal requirements of exocytosis, relatively little is known about the morphological changes accompanying this response in electro permeabilized cells. In this study, we determined that electropermeabi lization of human neutrophils by itself caused only minor changes in t he morphology as determined by transmission electron microscopy. The s tructure of the plasma membrane did not show detectable changes, where as the cytoplasm was more electron lucent as compared to intact cells. Activation of intact neutrophils with formyl-methionyl-leucyl-phenyla lanine (FMLP), in the presence of cytochalasin B, caused the developme nt of invaginations of the plasma membrane. In contrast, activation of electropermeabilized cells with 1 mu M Ca2+ and/or 50 mu M GTP-gamma- S caused the development of vacuoles that did not seem to be in contac t (or had previously been in contact) with the extracellular environme nt. However, fusion of azurophilic and specific granules with these va cuoles clearly had taken place. The response characteristics of this f usion induced by Ca2+ and GTP-gamma-S were quite similar to those of t he direct fusion of granules with the plasma membrane. We conclude tha t in electropermeabilized human neutrophils, two processes involving g ranule fusion can be distinguished. First, a direct fusion of granules with the plasma membrane. Secondly, the fusion of granules leading to the formation of vacuoles, not in contact with the extracellular spac e.