Recombinant human alpha-2a interferon promotes an atypical process of mast cell secretion with ultrastructural features suggestive for piecemeal degranulation.
Purified mast cells (MC), isolated from the rat peritoneum, were stimulated in vitro with recombinant human IFN-alpha 2a (rhIFN-alpha 2a) and studied ultrastructurally. Quantitative determination of histamine release was also performed. The following ultrastructural features were observed: (1) dilation of single granules, leading to the formation of cytoplasmic cavities filled with dissolved or eroded matrices; (2) induction of partially empty, nonfused granule containers close to unaltered resting granules, a process very suggestive of piecemeal degranulation; (3) focal exocytosis, characterized by opening of single granules to the cell exterior and/or fusion of a few granules into small secretory channels. Histamine release was slightly increased in rhIFN-alpha 2a-treated MC, although not to significant levels. These results indicate that rhIFN-alpha 2a induces a characteristic pattern of degranulation in rat peritoneal MC and that a small proportion of rhIFN-alpha 2a-stimulated MC shows ultrastructural features suggestive for piecemeal degranulation.
Crivellato
Enrico
E
Department of Medical and Morphological Research, Anatomy Section, University of Udine Medical School, Udine, Italy.
Candussio
Luigi
L
Mallardi
Franco
F
Ribatti
Domenico
D
D000818:Animals; D015550:Cell Degranulation; D002478:Cells, Cultured; D006636:Histamine Release; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology*; D008407:Mast Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010537:Peritoneum; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins; D013268:Stimulation, Chemical
D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011994:Recombinant Proteins