Page 1159 - Veterinary Immunology, 10th Edition
P. 1159
It is commonly observed that tumor-bearing animals are
VetBooks.ir immunosuppressed (Fig. 35.4). This is most clearly seen in animals
with lymphoid tumors; for example, B cell tumors tend to suppress
antibody formation, whereas T cell tumors suppress cell-mediated
immune responses and NK cell activity. This immunosuppression
can include defects in antigen recognition, in co-stimulation, and in
cytokine production. Immunosuppression in animals with
chemically induced tumors is due in part to production of
immunosuppressive molecules such as prostaglandin E by tumor
2
cells or tumor-associated macrophages. The presence of actively
growing cancer cells represents a severe protein drain on an animal.
This protein loss may also be immunosuppressive. Some tumors
contain areas of cellular necrosis. This necrosis releases potassium
ions that suppress T effector function.
FIG. 35.4 Some of the immunosuppressive effects of cancers.
Some tumor-derived molecules may redirect macrophage
activities so that they promote tumor growth. Thus tumor-derived
IL-4, IL-6, IL-10, TGF-β, prostaglandin E , and macrophage colony-
2
stimulating factor can deactivate or suppress the activation of
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