Question

A helper T cell response to a protein antigen requires the participation of antigen-presenting cells that express which of the following types of molecules?

A. Class II MHC and costimulators
B. Class I MHC and CD4
C. Class II MHC and CD8
D. CD4 and costimulators
E. Class II MHC and CD4

Answer 1

The helper T cell response to a protein antigen requires antigen-presenting cells that express Class II MHC molecules and costimulatory signals. The correct option is A.

Step-by-step explanation:

The student's question asks about the molecules required for a helper T cell to respond to a protein antigen. Helper T cells, also known as CD4+ T cells, require antigen-presenting cells (APCs) that express Class II MHC (Major Histocompatibility Complex) molecules and costimulatory signals to properly respond to antigens.

APCs such as macrophages, dendritic cells, and B cells express Class II MHC molecules on their surfaces. When these molecules are combined with a foreign antigen, they signal an invasion to the helper T cells.

CD4 is a co-receptor that enhances the interaction between the T-cell receptor and the Class II MHC-antigen complex. Therefore, the correct answer is A. Class II MHC and costimulators. Option A. is the correct one.