Page 629 - Veterinary Immunology, 10th Edition

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FIG. 20.12 The origins and properties of interleukin-10.

Oral administration of an antigen may induce pTreg cells. Treg
cells from the mesenteric lymph nodes of orally tolerant animals
secrete TGF-β, IL-4, and IL-10. This may account, in large part, for
tolerance to food antigens.

Treg cells are not the only way in which cellular control of
immune responses is exercised. Many of the regulatory activities of
T cells reflect the antagonistic functions of Th1 and Th2 cells. For

example, IFN-γ from Th1 cells can suppress IgE production,
whereas IL-10 from Th2 cells is suppressive for dendritic cell IL-12
production and thus for the production of Th1 cytokines.
In cattle, γ/δ T cells are a major regulatory T cell subset in
peripheral blood. They spontaneously secrete IL-10 and proliferate

in response to IL-10 and TGF-β. They can inhibit both antigen-
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specific and nonspecific proliferation of CD4 and CD8 T cells in
vitro.
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In horses, Tregs are FoxP3 , CD4 , and CD25 . They act in a
manner similar to other species by cell-cell contact and by IL-10 and
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TGF-β production. As in humans the circulating CD4 CD25 hi
population contains tTreg cells, while pTreg cells can be induced in
vitro by appropriate stimulation.

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hi
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Pigs possess CD4 CD25 FoxP3 Tregs that produce
immunosuppressive IL-10. They require IL-2 for activation, but
excessive IL-2 may reduce their suppressive activity.

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