Question

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-LewisX

Answer 1

The most likely defective protein in neutrophils that can roll but not arrest or migrate across the endothelium is an integrin, a protein essential for cell adhesion in the immune response, pointing to a type of inherited immunodeficiency. Option D.

Step-by-step explanation:

Immunodeficiency diseases impact the body's ability to fight off infections and potentially allow pathogens or cancers to proliferate unchecked. In the case described, where neutrophils can slowly roll along the endothelial cells but cannot arrest or migrate across, the most likely deficient protein in these immune cells is an integrin.

Integrins are proteins that facilitate cell adhesion and are essential for neutrophil extravasation, which is the process by which neutrophils exit the bloodstream to reach infected tissue.

When integrins are deficient or not functioning correctly, the neutrophils are unable to form the strong adhesive interactions required for them to stop and migrate out of the blood vessel, resulting in a compromised immune response.

This deficiency can lead to repeated infections and difficulty in clearing infections, characteristic of certain types of inherited immunodeficiency disorders, such as leukocyte adhesion deficiency (LAD). Option D.