Leukocyte Circulation and Migration into Tissues Flashcards
What is Migration?
Leukocyte movement from blood into tissues
What is recirculation?
The ability of lymphocytes to repeatedly home to secondary lymphoid organs and reside there transiently and return to the blood
What is leukocyte homing?
Cell migration out of blood into peripheral tissues. Usually occurs in response to an infection or tissue injury
What is inflammation triggered by?
recognition of microbes and dead or injured tissues in the innate immune responses.
How do neutrophils and monocytes enter the tissues?
Through post capillary venules except parenchymal tissues which will enter through capillaries
What do myeloid leukocytes do?
Eliminate infectious pathogens clear dead tissue and repair damage
What are the four events of leukocyte recruitment?
- Tethering through interactions of selectins and integrins with ligans
- Rolling which allows chemokine receptors on leukocytes to bind chemokines on the endothelium
- Adhesion and arrest which occur from receptors signaling and activating intergrins on leukocytes which interact with ligands on endothelium and trigger A and A.
- Transmigration into the tissues where they can follow a chemokine gradient
What selectins allow for capturing and rolling?
E selectins
What mediates recruitment of neutrophils?
CXCL8 aka IL-8
What mediates recruitment of monocytes?
CCL2 aka MCP-1
What are the adhesion molecules in transmigration of leukocytes that allow for arrest?
VCAM-1 and ICAM-1
When cells have completed trans-endothelial migration what do they interact with and where?
Interact with chemokines in the basement membrane
What shape do cells adopt following diapedesis?
Amoeboid shape
Do healthy endothelial cells express adhesion molecules?
No they do not. They are activated by infection or injury by cytokines secreted by the local resident immune cells such as mast cells or macrophages.
What are addressins?
A set of adhesion molecules expressed ONLY on the surface of HEV’s
