Question

An individual has a viral infection. This particular virus infects respiratory epithelial cells. Virus-specific naive CD8⁺ T cells are activated and differentiate into CTLs. What conditions would be LEAST necessary for a CTL effector response to the virus-infected cells?

MHC expression by respiratory epithelial cells

B7 expression by respiratory epithelial cells

proteasomal degradation of viral proteins

inflammation in the respiratory epithelium

Answer 1

All nucleated cells express Class I MHC. when the cells get infected with the virus they process the antigen and express it on the cell membrane for the recognition by CTL. Binding occurs between the MHC I bounded antigen and CD8+ present on the CTL membrane. The binding is complemented with B7 on antigen-presenting cells and CD28 on CTL. This causes activation and proliferation of CTL which kills the infected cells after activation.

There is no need or least necessary for inflammation in the respiratory epithelium.

So option 4 is correct.