Exocytic responses of single leukaemic human cytotoxic T lymphocytes stimulated by agents that bypass the T cell receptor.

Cytotoxic T lymphocytes kill targets via secretion of lytic agents including perforin and granzymes. Recently, new methods have been developed to monitor cytotoxic T lymphocyte degranulation. These include detecting the appearance of lysosome-associated membrane protein on the cell's surface, and monitoring decreases in cellular perforin content.

Retention of peptide hormones during partial secretion in pituitary somatotrophs and corticotrophs.

The secretion of peptide hormones during exocytosis of an individual vesicle can result in either complete discharge of vesicle content or can occur in a partial manner in which some hormone is retained during transient fusion. In anterior pituitary lactotrophs, the retained hormone prolactin was internalized and recycled into a pool of vesicles that underwent preferential use during subsequent exocytic stimulations [Bauer et al., (2004) J Cell Sci.

Recycling of intact dense core vesicles in neurites of NGF-treated PC12 cells.

Exocytic fusion in neuroendocrine cells does not always result in complete release of the peptide contents from dense core vesicles (DCVs). In this study, we use fluorescence imaging and immunoelectron microscopy to examine the retention, endocytosis and recycling of chromogranin B in DCVs of NGF-treated PC12 cells. Our results indicate that DCVs retained and retrieved an intact core that was available for subsequent exocytic release.

Retention and stimulus-dependent recycling of dense core vesicle content in neuroendocrine cells.

We have used fluorescence imaging of individual exocytic events in combination with immunogold electron microscopy and FM1-43 photoconversion to study the stimulus-dependent recycling of dense core vesicle content in isolated rat pituitary lactotrophs. Secretory stimulation with high external [K(+)] resulted in 100 exocytic sites per cell that were labeled by extracellular antibodies against the peptide hormone prolactin. Morphological analysis demonstrated that the prolactin was retained and internalized in intact dense cores.