The molecule indicated on this illustration of the first signal during the activation of a cytotoxic T cell (T_C) must be

Question

The molecule indicated on this illustration of the first signal during the activation of a cytotoxic T cell (T_C)must be

Quizplus · Accepted Answer

The activation of a cytotoxic T cell requires recognition of an antigen presented on Class I MHC molecules on the surface of an infected cell. Therefore, the molecule indicated in the illustration must be Class I MHC. Option B (Class II MHC) is incorrect because these molecules are involved in presenting antigens to helper T cells, not cytotoxic T cells. Option C (CD8 molecule) is incorrect because CD8 is a protein found on the surface of cytotoxic T cells and plays a role in recognizing and interacting with Class I MHC molecules. Option D (B7 protein) is incorrect because B7 proteins are expressed by antigen-presenting cells and interact with CD28 molecules on T cells, facilitating T cell activation, but are not directly involved in the initial recognition of antigens by cytotoxic T cells.

The Molecule Indicated on This Illustration of the First Signal