Page 360 - Veterinary Immunology, 10th Edition

VetBooks.ir Tertiary Lymphoid Organs

Within the body are found lymphoid structures that are structurally
similar to secondary lymphoid organs but develop in response to

microbial colonization and chronic immune stimulation. These are
organized masses of lymphocytes with clearly discrete T and B cell
regions that contain germinal centers and other lymphoid tissue
components. These can be called tertiary lymphoid organs. Good
examples of these develop in the intestinal wall in response to the

intestinal microbiota. Other examples are the lymphoid nodules
that develop in rheumatoid arthritis joints and in atherosclerotic
plaques. The initial trigger for their development probably comes

from stimulated fibroblasts that produce appropriate chemokines
attracting T cells, B cells and dendritic cells. Angiogenic factors
trigger the production of lymphatics and high endothelial venules.

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