Question

The antigen receptor on a T cell recognizes a degraded fragment of a protein (i.e., a peptide) bound to a specialized cell surface peptide-binding receptor called an MHC molecule. One key aspect of this system is that the peptides displayed on MHC molecules can be derived from intracellular proteins. This mode of antigen recognition is particularly important in allowing the adaptive immune response to detect infections by (select one)? Explain.

A. Large helminthic parasites in the gastrointestinal tract

B. Fungal infections in the skin epithelium

C. Fungi that form hyphae in the bronchial airways

D. Intracellular pathogens, such as viruses and some protozoa

E. Extracellular bacteria that colonize the lungs

Answer 1

This mode of antigen recognition is particularly important in allowing the adaptive immune response to detect infections by (select one)? Explain.

Answer: D. Intracellular pathogens, such as viruses and some protozoa.

The immune response to viral and other intracellualr pathogens is elicitated by adaptiveimmunity which involve both antibody-mediated and T cell-mediated immunity. Activation of T cells follows the recognition of intracellular pathogens as peptide fragments that is displayed on the surface of the T cells along with MHC molecules, a specialized host-cell glycoproteins that helps in delivering the pathogenic peptide to the cell surface.