A Nonfunctional CD4 Protein on a Helper T Cell Would

Question

A nonfunctional CD4 protein on a helper T cell would result in the helper T cell being unable to
A) respond to T-independent antigens.
B) lyse tumor cells.
C) stimulate a cytotoxic T cell.
D) interact with a class I MHC-antigen complex.
E) interact with a class II MHC-antigen complex.

Accepted Answer

The CD4 protein on a helper T cell interacts with class II MHC-antigen complexes on antigen-presenting cells (APCs), allowing the helper T cell to recognize and activate other immune cells. Without a functional CD4 protein, the helper T cell would not be able to interact with class II MHC-antigen complexes, and therefore would not be able to stimulate an immune response. Choices A, B, C, and D are all functions that are not directly related to the CD4 protein on helper T cells.