Page 1153 - Veterinary Immunology, 10th Edition

macrophages, and vascular endothelial cells. Cancers cannot spread
VetBooks.ir and metastasize without the support of these cells. Inflammatory

cytokines such as tumor necrosis factor-α (TNF-α) and
macrophages are often required for tumor development and

spread.
If a metastasizing tumor does not invade lymphoid organs, it
may escape immune surveillance. On the other hand, tumors that
invade lymph nodes can be divided into strongly and weakly

immunogenic types. Strongly immunogenic tumors elicit a strong T
cell response following processing by dendritic cells. Weakly
immunogenic tumors tend to grow as walled-off nodules that may
not be processed in sufficient amounts to trigger their destruction.

These are the most common tumors in humans. Inflammatory
tumor cells trigger dendritic cell activation and processing. On the
other hand, tumors that fail to generate inflammation may simply
be ignored by the immune system.

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