Degranulation of Individual Mast-Cells in Response to Ca2+ and Guanine-Nucleotides - an All-or-None Event

Hide, I., Bennett, J. P., Pizzey, A., Boonen, G., Barsagi, D., Gomperts, B. D., Tatham, P. E. R. (November 1993) Degranulation of Individual Mast-Cells in Response to Ca2+ and Guanine-Nucleotides - an All-or-None Event. Journal of Cell Biology, 123 (3). pp. 585-593. ISSN 0021-9525

URL: http://www.ncbi.nlm.nih.gov/pubmed/8227127
DOI: 10.1083/jcb.123.3.585

Abstract

Widespread experience indicates that application of suboptimal concentrations of stimulating ligands (secretagogues) to secretory cells elicits submaximal extents of secretion. Similarly, for permeabilized secretory cells, the extent of secretion is related to the concentration of applied intracellular effectors. We investigated the relationship between the extent of secretion from mast cells (assessed as the release of hexosaminidase) and the degranulation (exocytosis) responses of individual cells. For permeabilized mast cells stimulated by the effector combination Ca2+ plus GTP-gamma-S and for intact cells stimulated by the Ca2+ ionophore ionomycin, we found that exocytosis has the characteristics of an all-or-none process at the level of the individual cell. With a suboptimal stimulus, the population comprised only totally degranulated cells and fully replete cells. In contrast, a suboptimal concentration of compound 48/80 applied to intact cells induced a partial degree of degranulation. This was determined by observing the morphological changes accompanying degranulation by light and electron microscopy and also as a reduction in the intensity of light scattered at 90-degrees, indicative of a change in the cell-refractive index. These results may be explained by the existence of a threshold sensitivity to the combined effectors that is set at the level of individual cells and not at the granule level. We used flow cytometry to establish the relationship between the extent of degranulation in individual rat peritoneal mast cells and the extent of secretion in the population (measured as the percentage release of total hexosaminidase). For comparison, secretion was also elicited by applying the Ca2+ ionophore ionomycin or compound 48/80 to intact cells. For permeabilized cells and also for intact cells stimulated with the ionophore, levels of stimulation that generate partial secretion gave rise to bimodal frequency distributions of 90-degrees light scatter. In contrast, a partial stimulus to secretion by compound 48/80 resulted in a single population of partially degranulated cells, the degree of degranulation varying across the cell population. The difference between the all-or-none responses of the permeabilized or ionophore-treated cells and the graded responses of cells activated by compound 48/80 is likely to stem from differences in the effective calcium stimulus. Whereas cells stimulated with receptor-directed agonists can undergo transient and localized Ca2+ changes, a homogeneous and persistent stimulus is sensed at every potential exocytotic site in the permeabilized cells.

Item Type: Paper
Uncontrolled Keywords: EXOCYTOTIC REACTION CAPACITANCE MEASUREMENTS MONITORING EXOCYTOSIS HISTAMINE-RELEASE CALCIUM DEPENDENCE MODULATORS PROTEINS FUSION CA-2+
Subjects: organs, tissues, organelles, cell types and functions > cell types and functions > cell types > immune cell
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > immune cell
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > immune cell

organs, tissues, organelles, cell types and functions > cell types and functions > cell types > immune cell > mast cell
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > immune cell > mast cell
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > immune cell > mast cell
CSHL Authors:
Communities: CSHL labs
Depositing User: Matt Covey
Date: 1 November 1993
Date Deposited: 18 Apr 2016 20:34
Last Modified: 18 Apr 2016 20:34
PMCID: PMC2200119
Related URLs:
URI: http://repository.cshl.edu/id/eprint/32531

Actions (login required)

Administrator's edit/view item Administrator's edit/view item
CSHL HomeAbout CSHLResearchEducationNews & FeaturesCampus & Public EventsCareersGiving