Immune Privileged Sites, Such as the Brain, the Eye, and the Testis

question 6

Multiple Choice

Immune privileged sites, such as the brain, the eye, and the testis, are often the targets of autoimmune attack. Thus, once effector T cells are generated that have specificity for autoantigens expressed in these tissues, the effector cells can gain entry to the tissue and cause tissue damage. However, under normal circumstances, the priming and differentiation of effector cells specific for antigens found in the brain, for example, is generally prevented. This is because 'immune privileged' sites:

• A) Express antigens that never leave the tissue where they are produced
• B) Are surrounded by tissue barriers that block all lymphocyte trafficking
• C) Express the cell death receptor, Fas
• D) Express the cytokine, TGF-\(\beta\)
• E) Promote the differentiation of T_H17 cells

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Definitions:

Pheromones

Chemical substances produced and released into the environment by an animal, affecting the behavior or physiology of others of its own species.

Chemical Signals

Molecules released by cells that are used to communicate with other cells, affecting their behavior or physiology.

Pheromones

Chemical signals released by an organism to affect the behavior or physiology of other members of the same species.

First Messenger

A signaling molecule that binds to a receptor on the surface of a cell and triggers a biochemical cascade that conveys signals inside the cell.