Page 658 - Veterinary Immunology, 10th Edition

between the rumen and the immune system. The ruminal
VetBooks.ir lymphatics drain to many lymph nodes (Fig. 21.5). Toll-like

receptors (TLRs) such as TLR4, cytokines such as IL-1β and IL-10,
and caspase-1 can be found in the ruminal walls suggesting that

inflammation can readily occur here. Interferon-γ is found in
ruminal contents as are T and B cells. It appears that the ruminal
microbiota may communicate with its associated lymphoid tissues
and so promote regulatory responses. There is little evidence that

the ruminal microbiota directly shapes the development of the
immune system but it has been suggested that the complex innate
immune systems of ruminants, especially their high diversity of
antimicrobial peptides, may have evolved in response to this source

of microbial invasion.

FIG. 21.5 The lymphatic drainage of the rumen. The rumen is an
organ specialized for the fermentation and digestion of complex
plant polysaccharides. It is lined by stratified squamous epithelium
and is thus generally impermeable to most invading
microorganisms. However, leakage is inevitable, and as a result,
ruminants have large numbers of lymph nodes located where they
can trap any ruminal escapees. (From Sisson S [Revised by Grossman JD]:
Anatomy of the domestic animals, ed 4, Philadelphia, 1953, Saunders.)

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