CTLA-4,expressed by regulatory T cells and activated effector T cells,is crucial for self-tolerance as well as regulation of T cell responses of foreign antigens.Which of the following is a property of CTLA-4 that is important for its function?
A)CTLA-4 binds to CD28 and blocks its function.
B)CTLA-4 binds B7-1 and B7-2 with high affinity blocking their binding to CD28.
C)CTLA-4 binds class I MHC and blocks it ability to bind peptides.
D)CTLA-4 binds IL-2,preventing IL-2 binding to the IL-2 receptor.
E)CTLA-4 binds to IgG,preventing IgG biding to antigens.

Question

Quizplus · Accepted Answer

CTLA-4 expressed on the surface of regulatory T cells,or on recently activated naïve T cells competitively binds the B7 proteins on dendritic cells,and prevents B7 proteins from binding to CD28.Therefore the naïve T cells are not co-stimulated,leading to anergy or death of the T cells.CTLA-4 does not bind CD28,MHC proteins,IL-2,or IgG.

CTLA-4,expressed by Regulatory T Cells and Activated Effector T Cells,is