MHC I and MHC II

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which type of cells have MHC II molecules on their surface?

Effector T cells

All nucleated cells

Macrophages, dendritic cells, and B cells (correct)

Mature red blood cells

What is the function of MHC I molecules?

Present self and non-self pathogen antigens for initial T cell activation

Present self and non-self pathogen antigens to B cells for antibody production

All of the above

Present non-self pathogen antigens to effector T cells for cellular immunity (correct)

What is the composition of MHC I molecules?

One protein chain, α

One β protein chain and one γ2 microglobulin protein

One α protein chain and one β2 microglobulin protein (correct)

Two protein chains, α and β

What is the composition of MHC II molecules?

Two protein chains, α and β Signup and view all the answers

Where is the antigen-binding cleft located in MHC molecules?

Near the outermost portion of the dimer Signup and view all the answers

What is the function of MHC II molecules?

Present self and non-self pathogen antigens for initial T cell activation Signup and view all the answers

What is the role of dendritic cells in antigen presentation?

Recognize and attach to a pathogen cell Signup and view all the answers

What is the name of the process where antigen processing begins in a phagosome?

Phagolysosome formation Signup and view all the answers

What type of antigen epitopes are presented to T cells by MHC II?

Protein antigen epitopes Signup and view all the answers

What is the name of the mechanism by which epitopes are selected for processing and presentation by an APC?

Immunodominance Signup and view all the answers

What happens to the most antigenic, immunodominant epitopes after they have been processed by an APC?

They associate within the antigen-binding cleft of MHC II molecules Signup and view all the answers

What is the name of the process where MHC I molecules present self and non-self pathogen antigens to effector T cells?

Cellular immunity Signup and view all the answers

Which cells have MHC II molecules on their surface?

Antigen-presenting cells Signup and view all the answers

What is the function of MHC I molecules in cellular immunity?

Present self and non-self pathogen antigens to effector T cells Signup and view all the answers

What is the composition of MHC I molecules?

A longer α protein chain and a smaller β2 microglobulin protein Signup and view all the answers

What is the composition of MHC II molecules?

Two protein chains, α and β Signup and view all the answers

What is the function of MHC II molecules in initial T cell activation?

Present non-self pathogen antigens for initial T cell activation Signup and view all the answers

What is the antigen-binding cleft for MHC I formed by?

α1 and α2 domains Signup and view all the answers

What is the antigen-binding cleft for MHC II formed by?

α1 and β1 domains Signup and view all the answers

What type of antigens are presented to T cells by MHC II?

Protein antigen epitopes Signup and view all the answers

Where are the most antigenic, immunodominant epitopes presented for T cell activation?

On the surface of antigen-presenting cells Signup and view all the answers

What is the function of lysosomes in antigen processing?

Contain antimicrobial enzymes and chemicals Signup and view all the answers

What cells recognize and attach to a pathogen cell for antigen processing?

Antigen-presenting cells Signup and view all the answers

What is the mechanism by which epitopes are selected for processing and presentation by an APC?

Complicated and not well understood Signup and view all the answers

Study Notes

Major Histocompatibility Complex: MHC I and MHC II Molecules

Major Histocompatibility Complex (MHC) genes code for MHC molecules found on all nucleated cells of the body except mature red blood cells.
MHC I and MHC II molecules are involved in adaptive immunity.
MHC I molecules present self and non-self pathogen antigens to effector T cells for cellular immunity, whereas MHC II molecules present non-self pathogen antigens for initial T cell activation.
MHC I molecules are composed of a longer α protein chain and a smaller β2 microglobulin protein; only the α chain spans the cytoplasmic membrane. MHC II molecules are composed of two protein chains, α and β, which are approximately similar in length.
Both MHC I and MHC II molecules have a cleft that serves as the antigen-binding site near the outermost portion of the dimer.
The antigen-binding cleft for MHC I is formed by the α1 and α2 domains, whereas for MHC II, the cleft is formed by the α1 and β1 domains.
MHC II molecules are found only on the surface of antigen-presenting cells (APCs) such as macrophages, dendritic cells, and B cells.
After dendritic cells recognize and attach 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.
Only protein antigen epitopes are presented to T cells by MHC II, and only a selection of the most antigenic or immunodominant epitopes are presented by APCs.
The mechanism by which epitopes are selected for processing and presentation by an APC is complicated and not well understood.
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.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge of the Major Histocompatibility Complex (MHC) and its role in adaptive immunity with this quiz on MHC I and MHC II molecules. Learn about the composition and antigen-binding cleft of each molecule, the presentation of self and non-self pathogen antigens, and the antigen processing and presentation by antigen-presenting cells (APCs). Challenge yourself to understand the selection mechanism for epitopes and the translocation process for T cell presentation. Take this quiz and become an M