Human basophil recovery from secretion. A review emphasizing the distribution of Charcot-Leyden crystal protein in cells stained with the postf ixation electron-dense tracer, cationized ferritin

Abstract

Basophils of two species, guinea pigs and humans, have been shown by ultrastructural analyses to recover from noncytotoxic secretory processes by conservation and synthetic mechanisms. In human basophils, an electron-dense tracer (cationized femtin) used after fixation labels membranes in continuity with plasma membranes at planes of section out of view, thereby indicating internalization of previously externalized granule membranes. Conservation of previously emptied granule containers that remain in the cytoplasm after secretion was associated with reaccumulation of electron-dense particles and condensation of these dense materials therein. Granuleand vesicle-poor, previously stimulated cells developed large numbers of cytoplasmic vesicles beneath plasma membranes, in expanding Golgi areas and in perigranular areas of the cytoplasm. Cytochemical labeling techniques to localize histamine and Charcot-Leyden crystal protein revealed reaccumulation of these two granule proteins in recovering human basophil granules. The mechanism(s) of their recovery likely involves both synthesis of new proteins and conservation by internalization of secreted proteins bound to cell surfaces.