Vesicular transport of peroxidase in human eosinophilic myelocytes

A. M. Dvorak, P. Estrella, T. Ishizaka

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


We performed ultrastructural cytochemistry to detect peroxidase in developmentally arrested human eosinophilic myelocytes. Human umbilical cord blood mononuclear cells were cultured for 21 days in the presence of murine- derived conditioned media, resulting in the development of eosinophilic myelocytes. Unlike normally developing eosinophilic myelocytes, which contain peroxidase in synthetic organelles (i.e. cisterns surrounding the nucleus and bounded by the rough endoplasmic reticulum and Golgi structures) and in immature and mature granules, the developmentally arrested cells showed ultrastructural evidence of decreased synthesis and secretory transport of peroxidase. Thus, peroxidase was generally absent in the perinuclear and rough endoplasmic cisterns, in Golgi structures, in immature granules and in the matrix compartment of most mature granules. Rather, bicompartmental specific granules displayed empty, peroxidase-negative matrix and central, peroxidase-negative core material. Peroxidase was present in perigranular vesicles, some of which were attached to granules. Such peroxidase-loaded transport vesicles are similar to those that effect piecemeal degranulation of mature human eosinophils cultured in rhIL-5-containing media [1]. These findings establish vesicle-mediated piecemeal degranulation in the secretory repertoire of immature human eosinophils and suggest the possibility that eosinophilic myelocytes may participate in vivo in important physiological and/or pathological events that require selective secretion from the specific granule matrix compartment.

Original languageEnglish (US)
Pages (from-to)10-18
Number of pages9
JournalClinical and Experimental Allergy
Issue number1
StatePublished - 1994
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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