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Questions and Answers
Which cells have MHC II molecules on their surface?
What is the function of MHC I molecules?
What is the function of MHC II molecules?
What are the two classes of MHC molecules involved in adaptive immunity?
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What is the function of lysosomes in antigen processing?
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What is the antigen-binding site on MHC molecules?
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Which cells utilize cross-presentation?
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What is the initial step in antigen processing?
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What is the difference in structure between MHC I and MHC II molecules?
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What is the function of effector T cells in cellular immunity?
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What is the function of dendritic cells in antigen presentation?
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Which cells do not have MHC II molecules on their surface?
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Which cells have MHC II molecules on their surface?
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What is the function of MHC I molecules?
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Which cells present abnormal or nonself pathogen antigens to the effector T cells involved in cellular immunity?
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What is the difference between MHC I and MHC II molecules?
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Where is the antigen-binding site located on MHC molecules?
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What happens after a dendritic cell recognizes and attaches to a pathogen cell?
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What is cross-presentation?
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Which cells utilize cross-presentation?
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What is the function of MHC II molecules?
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Where does antigen processing begin?
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What is contained in lysosomes that fuse with the phagosome to create a phagolysosome?
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What is translocated to the cell surface of the dendritic cell for presentation to T cells?
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Study Notes
Antigen Presentation with Major Histocompatibility Complex (MHC) Molecules
- MHC genes code for MHC molecules found on the surface of all nucleated cells of the body, except mature red blood cells.
- There are two classes of MHC molecules involved in adaptive immunity, MHC I and MHC II.
- MHC I molecules are found on all nucleated cells; they present normal self-antigens as well as abnormal or nonself pathogens to the effector T cells involved in cellular immunity.
- MHC II molecules are only found on macrophages, dendritic cells, and B cells; they present abnormal or nonself pathogen antigens for the initial activation of T cells.
- Both types of MHC molecules are transmembrane glycoproteins that assemble as dimers in the cytoplasmic membrane of cells, but their structures are quite different.
- MHC molecules have a cleft that serves as the antigen-binding site near the “top” (or outermost) portion of the MHC-I or MHC-II dimer.
- After a dendritic cell recognizes and attaches to a pathogen cell, the pathogen is internalized by phagocytosis and is initially contained within a phagosome.
- Lysosomes containing antimicrobial enzymes and chemicals fuse with the phagosome to create a phagolysosome, where degradation of the pathogen for antigen processing begins.
- Once the most antigenic, immunodominant epitopes have been processed, they associate within the antigen-binding cleft of MHC II molecules and are translocated to the cell surface of the dendritic cell for presentation to T cells.
- MHC I molecules, found on all normal, healthy, nucleated cells, signal to the immune system that the cell is a normal “self” cell.
- If a cell becomes infected with an intracellular pathogen, protein antigens specific to the pathogen are processed in the proteasomes and bind with MHC I molecules for presentation on the cell surface.
- Cross-presentation is utilized if the intracellular pathogen does not directly infect APCs, in which antigens are brought into the APC by mechanisms normally leading to presentation with MHC II, but the antigen is presented on an MHC I molecule for CD8 T cells.
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Description
Test your knowledge on antigen presentation with Major Histocompatibility Complex (MHC) molecules with this informative quiz! From the different classes of MHC molecules to the antigen-binding site and processing, this quiz covers all the essential details on how our immune system recognizes and responds to pathogen invaders. Sharpen your understanding of MHC I and MHC II molecules and their roles in cellular immunity. Take this quiz and see how well you know about antigen presentation with Major Histocompatibility Complex (MHC)
