154. T-cell clones in an individual recognize peptides only when bound and displayed by that
individual’s MHC molecules on the surface of antigen presenting cells. This process is known as:
A. MHC selection.
B. MHC restriction.
C. MHC interaction.
D. MHC display.

MHC Restriction in T-Cell Immune Response: Definition and Importance

The immune system relies heavily on the specificity of T-cells to distinguish self from non-self, and a crucial concept in this process is MHC restriction. This mechanism ensures that T-cells only recognize antigens when they are presented in conjunction with the individual’s own MHC (Major Histocompatibility Complex) molecules.

What Is MHC Restriction?

MHC restriction is the phenomenon where T-cell receptors (TCRs) recognize and bind to peptide antigens only when they are presented by self-MHC molecules on the surface of antigen-presenting cells (APCs).

This principle was first discovered in mouse experiments where T-cell clones could not recognize viral peptides unless they were presented with the host’s own MHC molecules. It has since become a fundamental aspect of immunology.

Why Is MHC Restriction Important?

• Self-tolerance: Prevents T-cells from attacking the body’s own cells unless presented in the correct context.

• Pathogen specificity: Allows precise targeting of infected or abnormal cells.

• Vaccine design: Helps in predicting which antigens will effectively stimulate T-cell responses based on MHC types.

Key Terms:

• MHC Molecules: Proteins on the surface of cells that display peptide fragments.

• T-Cell Receptor (TCR): Recognizes the MHC-peptide complex.

• Antigen-Presenting Cells (APCs): Cells such as dendritic cells, macrophages, and B-cells that present antigens via MHC molecules.

Correct Answer:

B. MHC restriction

This is the scientifically correct term describing how T-cells are specific to antigens presented with self-MHC