Page 933 - Veterinary Immunology, 10th Edition

opsonins or chemoattractants.
VetBooks.ir off. M2 cells produce arginase. Arginase generates proline and
If migrating worms cannot be killed, at least they can be walled

polyamines. Proline and the polyamines are required for collagen

synthesis and can induce fibroblast proliferation. The granulomas
that develop around tissue helminths such as schistosomes or liver
fluke are driven by arginase from M2 cells.

Eosinophils and Parasite Destruction
Invading worms attract eosinophils. This is provoked by mast cell

or parasite-derived products, as well as by IL-5 and other cytokines
from Th2 cells. IL-5 from Th2 cells and GM-CSF from Th17 cells
mobilize bone marrow eosinophils, releasing large numbers into

the circulation. Chemokines such as the eotaxins also attract
eosinophils (Fig. 28.6). Eosinophils exposed to helminth antigens
can increase their expression of MHC class II and become antigen-
presenting cells. These antigen-presenting eosinophils are highly
effective in promoting Th2 responses against worm antigens.

FIG. 28.6 Photomicrograph of a lesion in horse skin caused by
allergy to migrating parasitic helminth larvae. The granular cells are
eosinophils, and their presence indicates the occurrence of a type I
hypersensitivity reaction.

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