This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Most important for diapedesis? \nSelect and explain. \nA. PECAM, B. Selectin, C. Integrin, D. Mucin like glycoprotein', 'role': 'user'}, {'content': "Answer: A \nExplanation: o Platelet endothelial cell adhesion molecule (PECAM or CD-31) is present on both endothelium and leukocytes.\no It is the major adhesive molecule for diapedesis.\nLeukocyte and endothelial adhesion molecules\no Leukocyte adhesion and transmigration\xa0are regulated largely by binding of complementary' adhesion\xa0molecules on the leukocyte & endothelial surface and by chemical mediators,\no Cytokines affect these processes by modulating expression of adhesion molecules so that leukocytes can\xa0firmly adhere to endothelium.\no There are four molecular families of adhesion receptors.\n1. Selectin\no Selectins function in the cell to cell interaction\xa0i.e., adhesion of leukocytes to endothelium,\no E-selectin\xa0(CD-62 E) is present on endothelial cells and it binds to sialyl-lewis, (a sialylated form\xa0of oligosaccharide on leukocytes).\no Endothelial cell expression of E-selection\xa0is a hallmark of acute cytokine-mediated inflammation,\no P-selectin\xa0(CD-62 P) is present on endothelium and platelets and it binds to sialyl-Lewis on\xa0leukocytes,\no L-selectin (CD-62 L) is present on leukocytes and it binds to mucin-like glycoprotein GlyCAM-1\xa0on endothelium.\n2. Immunoglobulin family\no Present on endothelium\no ICAM-l (intracellular adhesion molecule-1) binds to β2-integrins (VLA-4) of leukocytes,\no Platelet endothelial cell adhesion molecule (PECAM or CD-31) is present on both endothelium\xa0and leukocytes. It is the major adhesive molecule for diapedesis.\n3. Integrins\no Integrins promote cell-cell or cell-matrix interaction\xa0( in contrast to selectins\xa0that promote only\xa0cell-cell interaction)\xa0i.e., integrins helps in adhesion of leukocytes to endothelium and adhesion\nof leukocytes to an extracellular matrix such as fibronectin, vitronectin, activated\xa0complement,\no Present on leukocytes\no β1 - integrins (VLA-4) bind to VCAM-1 of endothelium,\no β2 - integrins (LFA-1 and MAC-1) bind to ICAM-l of endothelium.\n4. Mucin-like glycoprotein\no These glycoproteins are present in the extracellular matrix and on the cell surface,\no An example is Heparan sulfate, that serves as a ligand for the leukocyte adhesion molecule CD-44.", 'role': 'assistant'}]