Question

What do the epitopes for T lymphocytes look like?

a) They directly destroy T cell epitopes.
b) They help MHC molecules present epitopes.
c) They bind to epitopes and initiate T cell activation.
d) They are not involved in epitope recognition.

Answer 1

T lymphocytes recognize and bind to specific parts of antigens called epitopes, which are presented on APCs in association with MHC molecules. The binding of TCR to epitope-MHC complex initiates T cell activation.

Step-by-step explanation:

T lymphocytes recognize antigens with their antigen receptor, called the T cell receptor (TCR). The TCR binds to small, specific parts of the antigen called epitopes. The epitopes are presented on the surface of antigen-presenting cells (APCs), such as macrophages or dendritic cells, in association with major histocompatibility complex (MHC) molecules.

The MHC molecules help present the epitopes to the TCR on T lymphocytes. T lymphocytes have two types of co-receptors on their surface: CD4 and CD8. CD4+ T cells interact with MHC II molecules on APCs, while CD8+ T cells interact with MHC I molecules on infected cells.

Once the TCR on T lymphocytes binds to the epitope-MHC complex on the surface of APCs or infected cells, it initiates T cell activation, leading to the differentiation of T cells into different functional types, such as helper T cells or cytotoxic T cells.