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Final

study notes for lecture nine: coordinating immune cell encounters


Department
Immunology
Course Code
IMM250H1
Professor
Dana Philpott
Study Guide
Final

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Lecture NINE: COORDINATING IMMUNE CELL ENCOUNTERS
lymphocyte migration
*lymphatic systemQHWZRUNRIFRQGXLWVWKDWFDUU\DFOHDUIOXLG³O\PSK´
:lymphatic vessels are interspersed with organized lymphatic organs called lymph nodes
*efferent lymphatic : leaves the lymph nodes and returns to the blood for re-circulation
*afferent lymphatic: point of entry for lymph
: drains the tissues and brings lymph into the lymph nodes
*chemokine: (similar to a cytokine) soluble protein secreted by cells to communicate to other cells
: forms a gradient so that a cell can sense its way toward an appropriate location
: directs traffic of lymphocytes throughout the body
Ælymphocytes respond to chemokine gradients
Æthe chemokine gradient is emitted from the lymph nodes
*the chemokine by itself is not strong enough to draw the T cells
*adhesion molecule: proteins at the cell surface that mediates binding between 2 different cells
: in the case of lymphocytes flowing in the blood, allows lymphocytes to stick to entry points into lymph nodes
Æadhesion molecule on T cell surface binds with a receptor on the target cell surface
Æadhesion molecules tether
Æthe chemokine gradient + adhesion molecule interactions draws the T cell
*high endothelial venule (HEV): portal of entry for lymphocytes circulating in the blood to directly enter a lymph node
ÆDVO\PSKRF\WHVJRWKURXJKWKH+(9VWKH\³VHHHYHU\WKLQJWKH\QHHGWRVHH´VRWKH\FDQHVFDSHIURPWKHEORRG and enter the lymph node
lymphocytes
Æhave finger-like structures = microvilli that touch adhesion molecules
Æadhesion molecules are located at parts of the blood vessel wall adjacent to the lymph node
Æthese mechanisms allow tethering of these molecules to adjacent lymph nodes
Æthey respond to chemokine gradients
Æas lymphocytes travel in the blood, they interact with venule
Æchemokine secretion causes a slowing of the lymphocyte
Æthe adhesion receptor interaction allows the T cell to escape from blood circulation
Æit allows naive lymphocytes to enter the lymph node where there is the most antigen presented
*fever increases the intensity of adhesion molecules as well as chemokine secretion
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