HLA Molecules and Haemochromatosis

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Questions and Answers

What is the primary role of non-HLA class II molecules in relation to MHC class II molecules?

They form the groove on the cell surface for MHC class II molecules.

They are involved in the actual presentation of antigens on the cell surface.

They assist in the transportation of MHC class II molecules to the cell surface. (correct)

They mimic classical HLA II molecules to enhance immune response.

How do LNP2 and LNP7 contribute to the antigen processing pathway?

They regulate the conformation of non-HLA class II molecules.

They directly bind antigens to MHC class II molecules.

They act as carriers that transport class I molecules to the cell surface.

They are part of the immune proteasome that cuts proteins into small peptides. (correct)

What distinguishes class III molecules from class I and II molecules?

Class III molecules are exclusively membrane-bound.

Class III molecules are more heterogeneous and secreted. (correct)

Class III molecules have a similar function to HLA class I molecules.

Class III molecules are essential for cellular immune responses.

What does tapasine do within the endoplasmic reticulum?

It completes the binding of antigens to MHC class I molecules. Signup and view all the answers

Which statement is true regarding the polymorphism of HLA class III molecules compared to class I and II?

HLA class III molecules possess limited polymorphism compared to classes I and II. Signup and view all the answers

Which of the following belongs to the complement system found within the HLA complex?

C4 Signup and view all the answers

What is the primary importance of polymorphism in HLA/MHC genes during organ transplantation?

To ensure compatibility between donor and recipient Signup and view all the answers

Which cytokine is released by macrophages and is critical for the activation of cytotoxic T cells?

Lymphotoxin Signup and view all the answers

In the context of HLA molecule matching, which alleles are most critical to match?

HLA A, HLA B, and HLA DR Signup and view all the answers

Which enzyme associated with steroid biosynthesis is encoded by genes in the class III complex?

Hydroxylase Signup and view all the answers

What is the consequence of not properly matching biological identity in organ transplantation?

Organ rejection Signup and view all the answers

When looking for potential organ donors, which is NOT typically considered in the matching process?

Complement factor levels Signup and view all the answers

Which of the following statements is true regarding the HLA class II antigens?

They usually undergo matching for organ transplantation. Signup and view all the answers

What is cis-codominance in relation to HLA class II molecules?

It results in the formation of a molecule identical to that of a parent. Signup and view all the answers

What occurs during trans-codominance?

Chains from both parents combine in unique pairings. Signup and view all the answers

What role does the C28 transcriptional factor play in gene expression?

It enhances the expression of certain immune system genes. Signup and view all the answers

How many potential gene combinations can arise from the six genes mentioned in the context?

There can be up to twelve different combinations. Signup and view all the answers

What does the nude lymphocyte syndrome result from?

Defects in the genes responsible for HLA molecules. Signup and view all the answers

What effect do interferon gamma and type I have on the expression of C28?

They induce the expression of C28 in response to stimuli. Signup and view all the answers

What distinguishes HLA class II molecules from other classes?

They are composed of two distinct chains, alpha and beta. Signup and view all the answers

What is the underlying purpose of the different combinations of HLA molecules?

To increase the diversity of recognition capabilities in the immune system. Signup and view all the answers

What role does β2-microglobulin play in the synthesis of MHC class I molecules?

It substitutes the chaperonins, allowing peptide allocation. Signup and view all the answers

Which chaperonin is involved with MHC class I molecules before the synthesis of β2-microglobulin?

Calnexin and calreticulin Signup and view all the answers

How do peptides enter the reticulum in the context of MHC class I molecules?

By the action of TAP transporters. Signup and view all the answers

What is the primary function of MHC class II molecules as mentioned?

To present exogenous peptides derived from outside the cell. Signup and view all the answers

What process occurs during the formation of a phagosome in relation to exogenous peptide presentation?

It leads to the invagination of the membrane. Signup and view all the answers

Which structure is primarily responsible for post-translational modifications of MHC class I molecules?

Golgi apparatus Signup and view all the answers

What is the fate of proteins within the vesicles formed by the phagosome?

They undergo degradation without proteasome involvement. Signup and view all the answers

What is the role of tapasine in relation to MHC class I molecules?

It supports MHC class I molecules during peptide allocation. Signup and view all the answers

What is the primary function of the invariant chain in the MHC class II molecule synthesis?

To fill and protect the binding pocket of the MHC class II complex Signup and view all the answers

Which of the following molecules is responsible for maintaining the conformation of MHC class II molecules?

DM or DO molecules Signup and view all the answers

What occurs if MHC class II molecules begin binding endogenous peptides during their transport from the ER?

They will not be able to present exogenous peptides Signup and view all the answers

Which protein plays a crucial role in the degradation of the invariant chain to facilitate peptide binding?

Cathepsin Signup and view all the answers

The binding pocket of MHC class II molecules needs to bind what type of peptides?

Exogenous peptides from extracellular sources Signup and view all the answers

What is the consequence of the trimerization of the invariant chain?

Construction of HLA class II molecules (DP, DM, DO) Signup and view all the answers

What role do chaperonins play in the transport of MHC class II molecules?

Facilitating correct folding of the MHC class II molecules Signup and view all the answers

What happens to the clipped portion of the invariant chain after the MHC class II complex is formed?

It occupies the groove of MHC class II molecules Signup and view all the answers

What results from T cells recognizing the HLA molecule as foreign after organ transplantation?

The patient can experience organ rejection. Signup and view all the answers

What phenomenon describes the ability of a single MHC molecule to bind multiple different peptides?

MHC restriction Signup and view all the answers

Which outcome occurred when splenocytes from a strain A mouse were tested with autologous dendritic cells infected with LCMV?

Complete lysis of target cells was observed. Signup and view all the answers

What happens when TCRs encounter antigen-presenting cells from a different strain expressing the same viral antigen?

No lysis occurs due to MHC differences. Signup and view all the answers

How does the TCR's specificity impact T cell maturation in the thymus?

T cells that recognize HLA class I and class II are rescued. Signup and view all the answers

Which type of molecules can present different antigens besides proteins?

Lipids Signup and view all the answers

What was the purpose of conducting a cytotoxic assay with different target cells?

To assess the ability of T cells to recognize self and foreign antigens. Signup and view all the answers

What is the outcome when TCRs recognize self-peptides presented by self-MHC molecules?

T cells are allowed to mature and survive. Signup and view all the answers

Study Notes

HLA Molecules

HLA molecules (HLA-A, B, C, and others) are responsible for presenting antigens to T cells.
HLA molecules are highly polymorphic, meaning they show significant variation among individuals.
This polymorphism is crucial for immune responses and organ transplantation.
HLA-E, F, G present non-classical peptides, unlike their counterparts.
HLA-G is relevant during pregnancy to prevent the rejection of the fetus by the mother's immune system.
MIC-A and MIC-B are stress ligands.

Haemochromatosis

Mutations in the HFE gene cause haemochromatosis.
This disease leads to iron accumulation in cells.
The iron receptor binds transferrin and transports iron outside the cell.

HLA Class II Molecules

HLA Class II molecules are heterodimers composed of alpha and beta chains.
These molecules are highly polymorphic.
HLA Class II molecules are constitutively expressed by specific immune cells (dendritic, Langerhans, epithelial etc).
Induction of class II molecules also occurs in various cells due to factors such as cytokines.
HLA-DP, DQ, and DR genes coding for alpha and beta chains are highly polymorphic.

HLA Class II Co-dominance

HLA Class II alleles inherited from both parents are expressed.
The combination creates cis and trans co-dominance scenarios.
This increases diversity.

Nude Lymphocyte Syndrome

Genetic defects in CIITA cause a deficiency in the expression of MHC class II molecules.
This syndrome impairs T cell development and function, resulting in a serious immunodeficiency.
IFN-γ induces CIITA synthesis, increasing MHC class II expression.
Interferon gamma signaling is crucial for CIITA induction in various cells.

Antigen Presentation

MHC class I and II molecules present different peptides.
HLA Class I present endogenous peptide fragments.
HLA Class II presents exogenous peptide fragments processed in antigen presenting cells.
Non-classical HLA class II molecules (DM, DO) are involved in facilitating antigen presentation by MHC class II molecules.
The peptides are loaded inside a groove.

Antigen Processing

Proteasome processes protein antigens into peptides, then these peptides are transported to the ER.
In some cases, proteins are transported to the lysosomes for enzymatic degradation before being displayed on the MHC groove.
TAP-transporters are crucial for protein peptide transport.
Many proteins are targeted by ubiquitination for degradation by the proteasome.
Some peptides associated with MHC I or MHC II during cellular infections.

Lipids, Peptide presentation

CD1 molecules present lipids to T cells.
Lipids are presented to T cells via CD1 molecules (nonclassical HLA)

MHC Restriction

Demonstrated by Zinkernagel and Doherty's experiments.
The same viral peptide but different MHC molecules could lead to different cell responses.

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Description

Explore the functions and significance of HLA molecules in the immune system, along with the genetic basis of haemochromatosis. This quiz covers HLA polymorphism, their roles during pregnancy, and the consequences of iron accumulation due to mutations. Understand the link between HLA molecules and various immune responses.

HLA Molecules and Haemochromatosis

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Podcast

Questions and Answers

What is the primary role of non-HLA class II molecules in relation to MHC class II molecules?

How do LNP2 and LNP7 contribute to the antigen processing pathway?

What distinguishes class III molecules from class I and II molecules?

What does tapasine do within the endoplasmic reticulum?

Which statement is true regarding the polymorphism of HLA class III molecules compared to class I and II?

Which of the following belongs to the complement system found within the HLA complex?

What is the primary importance of polymorphism in HLA/MHC genes during organ transplantation?

Which cytokine is released by macrophages and is critical for the activation of cytotoxic T cells?

In the context of HLA molecule matching, which alleles are most critical to match?

Which enzyme associated with steroid biosynthesis is encoded by genes in the class III complex?

What is the consequence of not properly matching biological identity in organ transplantation?

When looking for potential organ donors, which is NOT typically considered in the matching process?

Which of the following statements is true regarding the HLA class II antigens?

What is cis-codominance in relation to HLA class II molecules?

What occurs during trans-codominance?

What role does the C28 transcriptional factor play in gene expression?

How many potential gene combinations can arise from the six genes mentioned in the context?

What does the nude lymphocyte syndrome result from?

What effect do interferon gamma and type I have on the expression of C28?

What distinguishes HLA class II molecules from other classes?

What is the underlying purpose of the different combinations of HLA molecules?

What role does β2-microglobulin play in the synthesis of MHC class I molecules?

Which chaperonin is involved with MHC class I molecules before the synthesis of β2-microglobulin?

How do peptides enter the reticulum in the context of MHC class I molecules?

What is the primary function of MHC class II molecules as mentioned?

What process occurs during the formation of a phagosome in relation to exogenous peptide presentation?

Which structure is primarily responsible for post-translational modifications of MHC class I molecules?

What is the fate of proteins within the vesicles formed by the phagosome?

What is the role of tapasine in relation to MHC class I molecules?

What is the primary function of the invariant chain in the MHC class II molecule synthesis?

Which of the following molecules is responsible for maintaining the conformation of MHC class II molecules?

What occurs if MHC class II molecules begin binding endogenous peptides during their transport from the ER?

Which protein plays a crucial role in the degradation of the invariant chain to facilitate peptide binding?

The binding pocket of MHC class II molecules needs to bind what type of peptides?

What is the consequence of the trimerization of the invariant chain?

What role do chaperonins play in the transport of MHC class II molecules?

What happens to the clipped portion of the invariant chain after the MHC class II complex is formed?

What results from T cells recognizing the HLA molecule as foreign after organ transplantation?

What phenomenon describes the ability of a single MHC molecule to bind multiple different peptides?

Which outcome occurred when splenocytes from a strain A mouse were tested with autologous dendritic cells infected with LCMV?

What happens when TCRs encounter antigen-presenting cells from a different strain expressing the same viral antigen?

How does the TCR's specificity impact T cell maturation in the thymus?

Which type of molecules can present different antigens besides proteins?

What was the purpose of conducting a cytotoxic assay with different target cells?

What is the outcome when TCRs recognize self-peptides presented by self-MHC molecules?

Study Notes

HLA Molecules

Haemochromatosis

HLA Class II Molecules

HLA Class II Co-dominance

Nude Lymphocyte Syndrome

Antigen Presentation

Antigen Processing

Lipids, Peptide presentation

MHC Restriction

Studying That Suits You

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