Electron microscopy elucidates eosinophil degranulation patterns in patients with eosinophilic esophagitis.
BACKGROUND
In patients with eosinophilic esophagitis (EoE), eosinophils accumulate and release granule proteins onto esophageal epithelium. However, little is understood about the mechanism of eosinophil degranulation.


OBJECTIVE
To determine and quantify eosinophil degranulation patterns, we studied esophageal biopsy specimens from both the proximal and distal esophagi of 9 randomly selected patients with EoE.


METHODS
The specimens were fixed in glutaraldehyde, embedded, sectioned, and imaged by means of transmission electron microscopy. Eosinophils and their granules were identified by their distinctive morphology, and all eosinophils and granules were imaged. A total of 1672 images from 18 esophageal specimens were evaluated and graded. Eosinophils were categorized based on membrane integrity and by cytoplasmic vesiculation as evidence of piecemeal degranulation. Granules were categorized based on reversal of staining (eosinophil granule core lightening) and localization within and outside the cells.


RESULTS
The results revealed that greater than 98% of eosinophils infiltrating the esophagus in patients with EoE demonstrate morphologic abnormalities ranging from granule changes with reversal of staining to marked cytoplasmic vesiculation to loss of cellular membrane integrity with cytolytic disruption and release of intact membrane-bound granules into the tissues. Approximately 81% of eosinophils showed membrane disruption. Extracellular granules were abundant in at least 70% of the images, and approximately 50% of these granules showed reversal of staining. On the basis of the prominence of tubulovesicular development, piecemeal degranulation appears closely related to the other morphologic changes seen in patients with EoE.


CONCLUSIONS
These findings reveal that eosinophils in esophageal biopsy specimens from patients with EoE are abnormal, with greater than 80% showing cytolysis, and therefore that evaluation by means of light microscopy after hematoxylin and eosin staining might not accurately reflect eosinophil involvement.
Department of Chemical Engineering, University of Utah, Salt Lake City, Utah. Electronic address: Hedieh.Saffari@utah.edu.
Hedieh
H
Saffari
Microscopy Core Facility, University of Utah, Salt Lake City, Utah.
Laura H
LH
Hoffman
Department of Internal Medicine, Division of Gastroenterology, University of Utah, Salt Lake City, Utah.
Kathryn A
KA
Peterson
Department of Internal Medicine, Division of Gastroenterology, University of Utah, Salt Lake City, Utah.
John C
JC
Fang
Department of Dermatology, University of Utah, Salt Lake City, Utah.
Kristin M
KM
Leiferman
Departments of Chemical Engineering and Internal Medicine, Division of Gastroenterology, and the Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah.
Leonard F
LF
Pease
Departments of Dermatology and Internal Medicine, University of Utah, Salt Lake City, Utah.
Gerald J
GJ
Gleich
D000328:Adult; D015550:Cell Degranulation / Q000276:immunology*; D057765:Eosinophilic Esophagitis / Q000276:immunology*; D004804:Eosinophils / Q000276:immunology* / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D055815:Young Adult
Eosinophilic esophagitis; activation; cytolysis; electron microscopy; eosinophils; piecemeal degranulation