a. What does the term “immune privileged” mean in relation to the CNS? Be sure to note which structure is responsible for the CNS being “immune privileged,” and how it works
b. What are the immune cells of the CNS and their functions? c. What branch of the immune system is absent from the healthy CNS?
Ans a) Immune privilege is the absence of strong inflammatory response on coming in contact with an antigen and lack of lymphatic drainage in an organ. Presence of blood brain barrier and lack of immune competent tissue macrophages and tissue dendritic cells protect CNS from immune-mediated harm and thus provide immune privilege. The CNS is protected from the entry of pathogens, immune cells, and some factors present in the blood through a physical blood-brain barrier maintained by tight junctions between brain endothelial cells, the basal lamina of these cells, and astrocyte endfeet processes. Therefore, antigens cannot readily enter the CNS.
Ans b ) Microglia is the immune cells in the brain, which comprise 80% of brain immune cells. And another cells identified in the brain are myeloid cells, T and B cells , monocytes/macrophages, dendritic cells.Microglia act as the immune defence cells of the CNS. and made of the same tissues as monocytes, which are a type of white blood cell that leaves the blood and sets up a front-line defence against invading organisms throughout the body.
CNS (central nervous system ) is protected by the immune system which further helps to ensure proper neural function and also of cells that reside directly in the CNS .The CNS consists of the brain and spinal cord.
Ans c) Lymphatic vessels of the immune system is absent from the healthy CNS