Leukocyte chemotaxis and adhesion Flashcards
Directional control of leukocyte migration is coordinated by tissue expression of what?
Adhesion molecules and chemical stimuli
What is Leukocyte diapedesis?
the movement of leukocytes out of the circulatory system and towards the site of tissue damage or infection.
What are the 4 steps in leukocyte diapedesis?
!. Circulating
- Tethering/rolling
- Firm adhesion
- Transmigration
What do leukocytes bind to in order to tether or roll?
Selectins
Where does L-selectin have constitutive expression?
Leukocytes
Where is P-selectin constitutive?
Platelets and endothelium
What happens to P-selectin on cell activation (histamine)?
Rapidly translocated to cell surface
Where is E-selectin found and what is it induced by?
Found on endothelial cells and induced by cytokines or LPS
What is E-selectin inhibited by?
Glucocorticoids
What happens in patients with Leukocyte adhesion deficicency-II?
Suffer recurrent infections
Rolling of leukocytes along endothelial cell surface activates what?
Integrins
What happens to leukocytes when integrins are in the high affinity state?
Firm adhesion
How many leukocyte heterodimers are there?
3
What happens to patients with Leukocyte adhesion deficiency I?
Suffer recurrent bacterial infections without pus
Why do patients with Leukocyte adhesion deficiency I suffer recurrent bac infections?
Leukocytes do not adhere to extracellular material or endothelium in vitro and are deficient in B2 integrin
