MHC Class 2 Molecules and Antigen Presentation

This video tutorial explains the processing and presentation of extracellular antigens. It covers how these antigens are internalized by antigen-presenting cells through endocytosis or phagocytosis, leading to the formation of endolysosomes where pathogens are digested. The assembly of MHC Class II molecules in the endoplasmic reticulum is detailed, including the role of the invariant chain. The process concludes with peptide fragments binding to MHC II molecules and being presented to T-cells, highlighting the role of the CD4 coreceptor.

What is the origin of extracellular or exogenous antigens?

• In the mitochondria

• Outside the host cell

• Inside the host cell

• Within the nucleus

Which cells are primarily responsible for internalizing extracellular antigens?

• Neurons

• Muscle cells

• Antigen-presenting cells

• Red blood cells

What is formed when an endosome fuses with a lysosome?

• Ribosome

• Golgi apparatus

• Nucleus

• Endolysosome

What is the role of lysosomal enzymes in the endolysosome?

• To transport nutrients

• To replicate DNA

• To digest pathogens into peptide fragments

• To synthesize proteins

Where are MHC Class 2 molecules synthesized?

• In the cytoplasm

• In the nucleus

• In the rough endoplasmic reticulum

• In the Golgi apparatus

What is the function of the invariant chain in MHC Class 2 molecules?

• To bind to pathogens

• To transport nutrients

• To replicate DNA

• To prevent self peptides from binding

What happens to the invariant chain during the transport of MHC Class 2 molecules?

• It remains intact

• It binds to pathogens

• It is transported to the nucleus

• It is digested, leaving a fragment called CLIP

What displaces the CLIP in the MHC Class 2 molecule?

• Peptide fragments of internalized antigens

• Lysosomal enzymes

• Golgi apparatus

• Self peptides

Which receptor on T-cells recognizes the peptide displayed by MHC Class 2 molecules?

• CD8 receptor

• T Cell receptor

• B Cell receptor

• Antibody receptor

What is the role of the CD4 coreceptor in the MHC Class 2 antigen presentation pathway?

• To bind to the beta 2 domain

• To transport MHC molecules

• To digest pathogens

• To bind to the alpha domain