CTLA-4 Is a Costimulatory Receptor on T Cells That Belongs

Multiple Choice

CTLA-4 is a costimulatory receptor on T cells that belongs to the same family as the CD28 costimulatory receptor.However, CTLA-4 is antagonistic to CD28.Which of the following could be a functional advantage of CTLA-4 expression within the immune response?

A) CTLA-4 competes with CD28 for ligand binding so that, if CD28 binds to its ligand, the response will be magnified.
B) CTLA-4 is often given to immunosuppressed individuals to trigger an immune response.
C) CTLA-4 limits the immune response of T_C and T_H cells after an infection has been cleared.
D) CTLA-4 limits T_C activity in healthy individuals during a viral infection.
E) CTLA-4 reduces the lag time between antigen presentation to a T_H cell and B-cell activation.