Question

A young adult is exposed to a virus that infects and replicates in mucosal epithelial cells of the upper respiratory tract. One component of the protective immune response to this viral infection is mediated by CD8+ cytolytic T lymphocytes (CTLs), which recognize and kill virus-infected cells. The CTLs can recognize and kill the infected cells because:

A. In response to interferon- secreted during the innate immune response to the virus, the mucosal epithelial cells express class II MHC, with bound viral peptides, on their cell surfaces.
B. Mucosal epithelial cells, like all nucleated cells, express class I MHC molecules and are able to process cytoplasmic viral proteins and display complexes of class I MHC and bound viral peptides on their cell surfaces.
C. Antibodies specific for viral antigens bind to these antigens on infected cell surfaces and engage Ig Fc receptors on the CTL, thereby targeting the CTL to the infected cells.
D. Virus-infected mucosal epithelial cells migrate to draining lymphoid tissues, where they present viral peptide antigens to naive CD8+ T cells.
E. Viral infection of the mucosal epithelial cells stimulates them to express E-selectin, which promotes CD8+ T cell adhesion.

Answer 1

CD8+ cytolytic T lymphocytes recognize and destroy virus-infected cells because these cells present viral antigens bound to class I MHC molecules on their surfaces, enabling CTLs to detect and target them.

Step-by-step explanation:

CD8+ cytolytic T lymphocytes (CTLs) can recognize and kill virus-infected mucosal epithelial cells because mucosal epithelial cells, like all nucleated cells, express class I MHC molecules. These cells are capable of processing cytoplasmic viral proteins and presenting complexes of class I MHC molecules bound with viral peptides on their cell surfaces. Once these viral antigens are presented on the surface of infected cells, CTLs can recognize these antigens as foreign and initiate the process of killing the infected cells. This immune response is critical for controlling and eliminating viral infections within the body.