Ultrastructural localization of vesicle-associated membrane protein(s) to specialized membrane structures in human pericytes, vascular smooth muscle cells, endothelial cells, neutrophils, and eosinophils

Vesicle-associated membrane proteins (VAMPs) are important to the trafficki ng of vesicles between membrane-bound intracytoplasmic organelles, in the f acilitation of neurosecretion, and in constitutive and regulated secretion in non-neuronal cells. We used a pre-embedding ultrastructural immunonanogo ld method to localize VAMPs to subcellular sites in human cells of five lin eages known to have cytoplasmic vesicles that may function in vesicular tra nsport. We found VAMPs localized to caveolae in pericytes, vascular smooth muscle cells, and endothelial cells of venules, to the vesiculo-vacuolar or ganelle, recently defined in venular endothelial cells, to the vesicle-rich intergranular cytoplasm and secretory granule membranes of neutrophils, an d to perigranular cytoplasmic secretory vesicles and secretory granule memb ranes in eosinophils. These specific localizations in five human vascular a nd granulocyte lineages support the notion that VAMPs have vesicle-associat ed functions in these cells.