All of Which is family of selectin, except –
Correct Answer: A selectin
Description: Ans. is 'c' i.e., A selectinLeukocyte and endothelial adhesion molecules o Leukocyte adhesion and transmigration are regulated largely by binding of complementary adhesion molecules on the leukocyte & endothelial surface, and by chemical mediators.o Cytokines affect these processes by modulating expression of adhesion molecules so that leukocytes can firmly adhere to endothelium.o There are four molecular families of adhesion receptors.1. SelectinSelectins function in cell to cell interaction i.e., adhesion of leukocytes to endothelium.o E-selectin (CD-62 E) is present on endothelial cells and it binds to sialyl-lewis. (a sialylated form of oligosaccharide on leukocytes).o Endothelial cell expression of E-selection is a hallmark of acute cytokine mediated inflammation.o P-selectin (CD-62 P) is present on endothelium and platelets and it bind to sialyl-Lewis on leukocytes.o L-selectin (CD-62 L) is present on leukocytes and it binds to mucin like glycoprotein G1yCAM- I on endothelium.Immunoglobulin familyo Present on endotheliumo ICAM-1 (intracellular adhesion molecule-1) binds to 132-integrins (VLA-4) of leukocytes.o Platelet endothelial cell adhesion molecule (PECAM or CD-31) is present on both endothelium and leukocytes. It is the major adhesive molecule for diapedisis.Integrinso Integrins promote cell-cell or cell-matrix interaction (in contrast to selectins that promote only cell-cell interaction) i.e., integrins helps in adhesion of leukocytes to endothelium and adhesion of leukocytes to extracellular matrix such as fibronectin, vitronectin, activated compliment.o Present on leukocytesintegrins (VLA-4) bind to VCAM-1 of endothelium.P2 - integrins (LFA-1 and MAC-1) bind to ICAM- 1 of endothelium.4. Mucin like glycoproteino These glycoproteins are present in the extracellular matrix and on cell surface.o Example is Heparan sulfate, that serves as ligand for the leukocyte adhesion molecule CD-44.
Category:
Pathology
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