Damage to neurons in patients with multiple sclerosis (MS) may be caused by autoreactive T cells that recognize peptides derived from myelin proteins presented by self MHC molecules. These autoreactive T cells secrete interferon (IFN)-ƴ and promote inflammation, which damages the myelin sheath surrounding neurons. The exact immunodominant epitopes recognized by autoreactive T cells in MS patents have been identified. One potential method of therapy for patients with MS is to administer therapeutic peptides that differ from the immunodominant epitopes by one or two amino acids. Which one of the following statements best describes the basis for this therapeutic approach?
A)The therapeutic peptides, called "altered peptide ligands," could inactivate T cells specific for myelin proteins, or drive them to differentiate into T cells that do not produce IFN-ƴ
B)The therapeutic peptides, called "altered peptide ligands," could interfere with processing of the natural myelin proteins by the patient's antigen-presenting cells.
C)The therapeutic peptides could bind to the TCRs of myelin-specific T cells but not to the self MHC molecules, thereby blocking T cell activation.
D)The therapeutic peptides could down-regulate MHC expression.
E)The therapeutic peptides could replace the damaged myelin and restore neuronal function.

Question

Quizplus · Accepted Answer

Altered peptide ligands are synthetic peptides in which the TCR contact residues have been changed, so that the peptide induces only partial responses by the responding T cell. These peptides still bind to the same MHC molecules as the original peptides, but they can cause T cell inactivation (anergy) or change in the cytokines the T cell produces. Altered peptide ligands do not interfere with processing of the natural proteins nor can they bind to TCRs without being presented by MHC molecules. There is no basis to say that peptides can down-regulate major MHC expression or replace damaged proteins in the myelin sheath.

Damage to Neurons in Patients with Multiple Sclerosis (MS) May