You are rotating on the neurology service and are asked to complete the following
true and false test about brain immunity. 1. The brain is "immune privileged" and
provides barriers to any intrusion of peripheral vascular immune cells or their products
from crossing the blood-brain barrier; 2. The brain's lymphatics drain into the cervical
lymph nodes; 3. The brain can recruit immune cells from the overlying bone marrow;
4. The choroid plexus effectively blocks any peripheral blood immune cells from entering
the central nervous sytem. 5. The meninges can release immune cell-derived cytokines;
6. neuronal cells are passive bystanders when it comes to the regulation of CNS immunity.
ANSWERS: 1. False: there is a constant interchange between the brain and the peripheral vascular system. 2.True. The brain's lymphatics do drain into the cervical lymph nodes. 3. True. Soluble mediators do recruit immune cells from the overlying bone marrow. 4. False. The choroid plexus is one area of the brain that has no barrier to the external environment (other areas include the olfactory bulb, the Nucleus Tractus Solitarius, and the Area Postrema). 5. True. The meninges can release both proinflammatory cytokines such as TNF-alpha and IL-1 beta and antiinflammatory cytokines such as IL-4 and IL-10. 6. False. Neurons are in constant communication with other neurons, astrocytes, microglia, oligodendrocytes and oligodendrocyte precursors. The microglia are the main immune cells of the CNS, cleaning up cellular debris and monitoring and removing unwanted synapses (synaptic pruining).
Bonus Question:
What is the name of this animal? Where in the United States is it found? What might you experience if you were bitten by this creature?
ANSWER: This is a Gila Monster which is endemic to the southwestern USA. It is poisonous, the bite inciting pain, swelling, redness, and, potentially necrosis; system symptoms may also develop. Rarely, the bite may be fatal.
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