Page 999 - Veterinary Immunology, 10th Edition

clarified, asthmatic cats respond well to corticosteroids and inhaled
VetBooks.ir bronchodilators as well as allergen avoidance. It is of interest to

note that there is a concordance between asthma in cats and in their
owners, suggesting the involvement of similar allergens.

FIG. 30.5 The pathogenesis of allergic asthma.

Asthma in humans is now recognized as a syndrome mediated
by several different pathogenic processes. Thus the majority of
cases are eosinophilic (>3% eosinophils in sputum) and regulated

by ILC2s and basophils. (ILC2s produce the type II cytokines IL-5
and IL-13). These cases are commonly allergic in origin and steroid
responsive. About 30% of human asthma cases are, however,
neutrophilic (>60% in sputum), associated with high Th17 cell
levels, and are often steroid unresponsive. Other asthma subtypes

may have both neutrophils and eosinophils or even neither, in
sputum. IL-33 is also generated in the lungs of many asthmatics. It
acts as an alarmin and activates ILC2 cells, basophils, and mast cells

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