Following an acute virus infection in which the host clears the virus by approximately one week post-infection, a population of virus-specific memory CD8 T cells is maintained and can be detected for months to years post-infection. In mice with a knockout of a single cytokine, virus-specific memory CD8 T cells cannot be maintained, and disappear over time as shown in Figure.
The most likely identity of the cytokine that is missing in these knockout mice is:
A) IL-15
B) IL-2
C) IL-21
D) IL-23
E) IL-4

Question

Following an acute virus infection in which the host clears the virus by approximately one week post-infection, a population of virus-specific memory CD8 T cells is maintained and can be detected for months to years post-infection. In mice with a knockout of a single cytokine, virus-specific memory CD8 T cells cannot be maintained, and disappear over time as shown in Figure.  
The most likely identity of the cytokine that is missing in these knockout mice is:
A) IL-15 
B) IL-2 
C) IL-21 
D) IL-23 
E) IL-4

Quizplus · Accepted Answer

IL-15 is a cytokine that plays a critical role in the survival and maintenance of memory CD8 T cells. In mice with a knockout of IL-15 or its receptor, virus-specific memory CD8 T cells cannot be maintained and disappear over time, as shown in the figure. Therefore, IL-15 is the most likely cytokine that is missing in these knockout mice.

Following an Acute Virus Infection in Which the Host Clears