Immunodeficiency diseases occur when individuals have defects in leukocyte adhesion to inflamed endothelial cells, thereby impeding the extravasation of phagocytes into infected tissues. When neutrophils from one class of these patients were isolated and tested using in vitro assays for neutrophil-endothelial cell interactions and extravasation, it was found that the neutrophils could slowly roll along the endothelial vessel wall but were unable to arrest and migrate across the endothelium. The most likely protein deficient in these neutrophils is: A) ICAM-1 or ICAM-2 B) P-selectin C) E-selectin D) An integrin E) Sulfated sialyl-Lewis^X

Question

Quizplus · Accepted Answer

The inability of neutrophils in the immunodeficiency patients to arrest and migrate across the endothelium suggests a defect in integrins, which are necessary for firm adhesion and transmigration of leukocytes through the endothelium. ICAM-1 and ICAM-2, P-selectin, and E-selectin are involved in the initial rolling of neutrophils along the endothelial surface, but not in subsequent adhesion and migration, which require integrins. Sulfated sialyl-Lewis^X is a sugar molecule that binds to selectins, but it is not a protein and not involved in the subsequent steps of neutrophil extravasation.

Immunodeficiency Diseases Occur When Individuals Have Defects in Leukocyte Adhesion