Eosinophils Flashcards
Eosinophils represent ____% of human blood leukocytes.
Eosinophils represent 1-7% of human blood leukocytes.
Types of eosinophil granule
primary
secondary/specific
small
secretory
Charcot-Leyden crystals
The Charcot-Leyden protein is present in Eosinophil primary granules. They form hexagonal bipyramidal crystal aggregates when released. These may be observed in sputum from eosinophilic inflammation.
Eosinophil lipid bodies
Eosinophils and many other leukocytes contain lipid droplets which are surrounded by eicosanoid-forming enzymes such as 5-LOX, LTC4S, and COX-2.
Distinctive eosinophil granule contents
MBP-1. MBP-2. eosinophil peroxidase (EPO), eosinophil cationic protein (ECP, a ribonucease), and eosinophil-derived neurotoxin (EDN, also a ribonuclease).
Piecemeal degranulation
Vesicular transport from the granules in the absence of classical exocytosis
Eosinophils may release certain factors via this mechanism
Factors regulating eosinophil expansion and differentiation
IL-5
IL-4
IL-13
GM-CSF
IL-3
Eosinophil chemotaxis
IL-4 binds receptors on endothelium.
Endothelium releases eotaxins 1, 2, and 3.
These bind to CCR3 on eosinophils.
IL-13 in allergic inflammation
Regulator of Th2 cell differentiation and survival, allergen-induced airway inflammation, and goblet cell metaplasia
Th1 chemotactic agents
CXCL9 and CXCL10
RANTES
Stimulates both neutrophil and eosinophil chemotaxis
Eosinophils in wound repair
Rich source of TGFβ
Associated with epithelial cell hyperplasia, angiogenesis, and fibrosis in late inflammatory phases
Unique eosinophil markers
IL-5Rα, CD34, CD38, IL-3Rα
Eosinophil development factors
GATA-1
C/EBPα
C/EBPε
PU.1
Eotaxins
Eotaxin-1 (CCL11)
Eotaxin-2 (CCL24)
Eotaxin-3 (CCL26)
RANTES (CCL5)
