Page 934 - Veterinary Immunology, 10th Edition

Eosinophils express many different PRRs including TLR1-5,
VetBooks.ir TLR7, TLR9, NOD1, NOD2, and dectin-1. When these are

stimulated, they trigger an oxidative burst, increase adhesiveness,
and release IL-1, IL-6, TNF-α, and GM-CSF, as well as their

cytotoxic granule contents (see Fig. 29.18).
Eosinophils employ Fc receptors to bind antibody-coated worms,
they then degranulate and release their granule contents directly
onto the worm cuticle (Fig. 28.7). These contents include oxidants,

nitric oxide, lysophospholipase, and phospholipase D. Major basic
protein, the crystalline core of the eosinophil specific granules, can
damage the cuticles of schistosomula, Fasciola, and Trichinella.
Eosinophil cationic protein and eosinophil neurotoxin are

ribonucleases that are lethal for helminths. It is important to point
out, however, that some larval worms may evade destruction by
eosinophils. For example, larvae of Toxocara canis simply shed their
outer coat together with the attached cells.

FIG. 28.7 Some of the molecules released from eosinophils that
cause damage to the cuticle of parasitic helminths.

Eosinophil granules released from cells remain functional. These
free granules express membrane receptors for IFN-γ and eotaxins,
that when triggered, stimulate the granules to secrete their contents.

Thus eosinophil granules function autonomously to contribute to
the defenses against helminths. Eosinophils also generate
extracellular NETs using released mitochondrial DNA.
Many nematodes are damaged or killed by eosinophil toxic

products, supporting the idea that eosinophils serve a protective
function. Nevertheless, this may not apply to all worms. For

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