Ultrastructural localization of major basic protein in the human eosinophil lineage in vitro

A. M. Dvorak, T. Furitsu, P. Estrella, L. Letourneau, T. Ishizaka, S. J. Ackerman

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We examined the ultrastructural localization of (a) secondary granule matrix protein-eosinophil peroxidase (EPO)-by cytochemistry, (b) a secondary granule core protein (major basic protein, MBP) by immunogold labeling, and (c) a primary granule protein (the Charcot-Leyden crystal protein, CLC protein) by immunogold labeling in eosinophilic myelocytes (EMs) and mature, activated eosinophils that differentiated from umbilical cord blood progenitors cultured in the presence of recombinant human interleukin-5 (rhIL-5). These studies provide the first substructural localization of MBP to condensing cores of immature secondary granules of EMs, as well as identification of unicompartmental, MBP-rich secondary granules that are devoid of matrix compartments and EPO content and are not primary granules by virtue of their lack of CLG protein. These granules occur in quantity in IL- 5-activated mature human eosinophils, which have previously been shown to actively transport EPO from the matrix compartments of their secondary granules to the extracellular milieu in smooth membrane-bound cytoplasmic vesicles, a secretory process termed piecemeal degranulation, whereby eosinophils progressively empty cytoplasmic granules of their contents in the absence of classical granule extrusion.

Original languageEnglish (US)
Pages (from-to)1443-1451
Number of pages9
JournalJournal of Histochemistry and Cytochemistry
Issue number11
StatePublished - 1994
Externally publishedYes


  • Charcot- Leyden crystal protein
  • Cytochemistry
  • Development
  • Eosinophil peroxidase
  • Granulogenesis
  • Human eosinophils
  • Major basic protein
  • Piecemeal degranulation
  • Secretion
  • Ultrastructural immunogold localization
  • rhIL-5-containing cultures

ASJC Scopus subject areas

  • Anatomy
  • Histology


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