8.2 Immunotolerance

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What is the name of the pathway that regulates T cell deletion by apoptotic cell death?

Inflammatory pathway

Mitochondrial pathway (correct)

Extrinsic pathway

Apoptotic pathway

Which protein family is involved in initiating the mitochondrial pathway of T cell deletion?

BCL-2 family proteins (correct)

Tyrosine kinase receptors

G protein-coupled receptors

ATP-binding cassette transporters

What happens when BAX and BAK insert into the outer mitochondrial membrane during T cell deletion?

Reduction in cytochrome c leakage

Decreased mitochondrial permeability

Increased mitochondrial permeability (correct)

Activation of anti-apoptotic proteins

Which event leads to the activation of cytosolic enzymes called caspases during T cell deletion?

Release of cytochrome c from mitochondria (A) Signup and view all the answers

What type of signaling can induce or activate cytoplasmic proteins of the BCL-2 family during T cell deletion?

Receptor-mediated signaling (B) Signup and view all the answers

What is the purpose of peripheral tolerance mechanisms discussed in the text?

To maintain unresponsiveness to self antigens in peripheral tissues (D) Signup and view all the answers

Which cell type is responsible for actively suppressing the activation of lymphocytes specific for self and other antigens in peripheral tolerance?

Regulatory T cells (Tregs) (A) Signup and view all the answers

What is deletion or negative selection in the context of central T cell tolerance?

Death of immature T cells recognizing antigens with high avidity in the thymus (A) Signup and view all the answers

In central T cell tolerance, where does negative selection of thymocytes primarily occur?

Thymic cortex (C) Signup and view all the answers

Which protein plays a crucial role in controlling autoimmune diseases by regulating peripheral tissue antigens in the thymus?

Autoimmune regulator protein (AIRE) (A) Signup and view all the answers

What characterizes autoimmune diseases that are under the control of autoimmune regulator protein (AIRE)?

Damage to multiple endocrine organs and skin (A) Signup and view all the answers

What is the principal function of regulatory T cells?

To suppress immune responses (C) Signup and view all the answers

Which transcription factor is expressed by CD4+ FOXP3+ CD25high T cells?

FOXP3 (A) Signup and view all the answers

How are the majority of Tregs in lymphoid tissues derived?

From self antigen expression (A) Signup and view all the answers

What is required for the generation of some Tregs?

TGF-β (B) Signup and view all the answers

What are the two major pathways of apoptosis?

Mitochondrial (intrinsic) pathway and death receptor (extrinsic) pathway (D) Signup and view all the answers

What happens to T lymphocytes that repeatedly stimulated by antigens?

They die by apoptosis (B) Signup and view all the answers

Which pathway involves the activation of cytoplasmic adaptor proteins and procaspase-8?

Extrinsic pathway (A) Signup and view all the answers

Which receptor-ligand pair is most important in inducing apoptosis in T cells?

FAS-FAS ligand (FASL) (D) Signup and view all the answers

Where does central B-cell tolerance mainly occur?

Bone marrow (C) Signup and view all the answers

What is the fate of mature B lymphocytes recognizing self antigens in peripheral tissues without T cell help?

Apoptosis (C) Signup and view all the answers

What mechanism renders some B lymphocytes anergic or leads to their apoptosis when recognizing self antigens?

Signaling by inhibitory receptors - CD22 (B) Signup and view all the answers

Which type of T lymphocytes function to control responses to self antigens in peripheral tissues?

T follicular regulatory (Tfr) cells (C) Signup and view all the answers

What happens to some immature T cells in the thymus when they encounter self antigens?

Negative selection (death) (D) Signup and view all the answers

In CD4+ T cells, what induces anergy?

Engagement of inhibitory receptors like CTLA-4 and PD-1 (C) Signup and view all the answers

"Receptor editing" may occur in B lymphocytes when:

"Immature B cells recognize multivalent self antigens" (B) Signup and view all the answers

"Peripheral tolerance" in B cells may involve each EXCEPT:

"Proliferation" (B) Signup and view all the answers

What mechanism causes mature CD4+ T cells to become unresponsive to an antigen?

Exposure to the antigen in the absence of costimulation (B) Signup and view all the answers

Which signal is required for full activation of T cells?

Recognition of costimulators by CD28 and recognition of the antigen by the TCR (C) Signup and view all the answers

What occurs in anergic cells that blocks TCR-induced signal transduction?

Blockage of TCR-induced signal transduction (D) Signup and view all the answers

What happens when T cells recognize self antigens in the absence of innate immune responses?

They engage inhibitory receptors of the CD28 family (B) Signup and view all the answers

Which of the following is NOT a mechanism that may function to induce and maintain the anergic state?

Recognition of costimulators by CD28 (D) Signup and view all the answers

What is the result of self antigen recognition without costimulation?

Activation of cellular ubiquitin ligases (D) Signup and view all the answers

What initiates the mitochondrial pathway of T cell deletion by apoptotic cell death?

Growth factor deprivation (B) Signup and view all the answers

Which proteins lead to increased mitochondrial permeability during T cell deletion?

BAX and BAK (A) Signup and view all the answers

What factor is crucial for the generation, survival, and functional competence of Regulatory T cells?

TGF-β (C) Signup and view all the answers

What activates cytosolic enzymes called caspases during T cell deletion?

Release of pro-apoptotic mitochondrial proteins into the cytosol (B) Signup and view all the answers

What results from the insertion of BAX and BAK into the outer mitochondrial membrane during T cell deletion?

Leakage of pro-apoptotic mitochondrial proteins (C) Signup and view all the answers

Which pathway of apoptosis is triggered by T lymphocytes recognizing antigens with high affinity or self?

Mitochondrial pathway (B) Signup and view all the answers

What is the primary function of Regulatory T cells?

Suppress immune responses (A) Signup and view all the answers

What type of stimuli can induce or activate cytoplasmic proteins of the BCL-2 family during T cell deletion?

Noxious stimuli (A) Signup and view all the answers

Which transcription factor is expressed by CD4+ FOXP3+ CD25high T cells?

FOXP3 (D) Signup and view all the answers

What cytokine is crucial for the survival and functional competence of Regulatory T cells?

IL-2 (A) Signup and view all the answers

In which tissues are the majority of Regulatory T cells thought to be derived from?

Thymus (D) Signup and view all the answers

What is the most important death receptor in T cells involved in apoptosis induction?

FAS (C) Signup and view all the answers

Which cell surface receptors are engaged by their ligands in the extrinsic pathway of T cell deletion?

TNF receptor superfamily (A) Signup and view all the answers

What is a homologous ligand to TNF in the context of T cell deletion?

CD95 (B) Signup and view all the answers

Which mechanism may render mature B lymphocytes recognizing self antigens in peripheral tissues unresponsive?

CTLA-4 engagement (D) Signup and view all the answers

What is the primary outcome when immature B lymphocytes recognize self antigens with high affinity in the bone marrow?

Receptor editing (D) Signup and view all the answers

What process occurs when T cells encounter self antigens without additional stimuli or repetitive stimulation?

Apoptosis (C) Signup and view all the answers

Which type of tolerance is induced in generative lymphoid organs when immature lymphocytes encounter self antigens?

Central tolerance (C) Signup and view all the answers

What occurs when mature B lymphocytes recognize self antigens in the absence of specific helper T cells?

Apoptotic death (A) Signup and view all the answers

Which event leads to the activation of downstream caspases during apoptosis induction in T cells?

Production of active caspase-8 (A) Signup and view all the answers

How are CD4+ T cells rendered anergic in the context of antigen recognition?

Anergy induction (A) Signup and view all the answers

What is the primary effect of anergy on self-reactive T cells?

The cells become unresponsive to the antigen (A) Signup and view all the answers

What is required for full activation of T cells?

Both signal 1 and signal 2 (A) Signup and view all the answers

What happens when T cells recognize self antigens in the absence of innate immune responses?

They engage inhibitory receptors of the CD28 family (A) Signup and view all the answers

What is NOT a mechanism that may function to induce and maintain the anergic state?

Anergic cells become hyperresponsive to the antigen (B) Signup and view all the answers

Which cells are primarily responsible for actively suppressing the activation of lymphocytes specific for self and other antigens in peripheral tolerance?

Regulatory T cells (D) Signup and view all the answers

What happens to TCR-associated proteins when self antigen recognition occurs without costimulation?

They are ubiquitinated and targeted for proteolytic degradation (B) Signup and view all the answers

What is the term for the unresponsiveness to an antigen that is induced by exposure to that antigen?

Immunotolerance (B) Signup and view all the answers

What are the antigens that induce tolerance called?

Tolerogens (A) Signup and view all the answers

What is the ability of the immune system to recognize and respond to foreign antigens but not to self antigens called?

Self-non-self discrimination (A) Signup and view all the answers

What is the term for the phenomenon where some developing T and B cells in every individual may express receptors capable of recognizing normal molecules in that individual?

Autoreactivity (B) Signup and view all the answers

What is the term for the process of eliminating and inactivating lymphocytes that express high-affinity receptors for self antigens?

Central tolerance (D) Signup and view all the answers

What is the term for the phenomenon where many self-reactive lymphocytes complete their maturation and are present in healthy individuals?

Imperfect tolerance (C) Signup and view all the answers

What is the term for the process of inducing self-tolerance in immature self-reactive lymphocytes in the generative lymphoid organs?

Central tolerance (C) Signup and view all the answers

What is the term for the process of inducing self-tolerance in lymphocytes in peripheral or mature sites?

Peripheral tolerance (C) Signup and view all the answers

What is the term for the property of the normal immune system that prevents reactions to self antigens?

Self-tolerance (D) Signup and view all the answers

What is the term for the experimental observation that animals that had encountered an antigen under particular conditions would not respond to subsequent exposures to the same antigen?

Immunotolerance (B) Signup and view all the answers

8.2 Immunotolerance

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Questions and Answers

What is the name of the pathway that regulates T cell deletion by apoptotic cell death?

Which protein family is involved in initiating the mitochondrial pathway of T cell deletion?

What happens when BAX and BAK insert into the outer mitochondrial membrane during T cell deletion?

Which event leads to the activation of cytosolic enzymes called caspases during T cell deletion?

What type of signaling can induce or activate cytoplasmic proteins of the BCL-2 family during T cell deletion?

What is the purpose of peripheral tolerance mechanisms discussed in the text?

Which cell type is responsible for actively suppressing the activation of lymphocytes specific for self and other antigens in peripheral tolerance?

What is deletion or negative selection in the context of central T cell tolerance?

In central T cell tolerance, where does negative selection of thymocytes primarily occur?

Which protein plays a crucial role in controlling autoimmune diseases by regulating peripheral tissue antigens in the thymus?

What characterizes autoimmune diseases that are under the control of autoimmune regulator protein (AIRE)?

What is the principal function of regulatory T cells?

Which transcription factor is expressed by CD4+ FOXP3+ CD25high T cells?

How are the majority of Tregs in lymphoid tissues derived?

What is required for the generation of some Tregs?

What are the two major pathways of apoptosis?

What happens to T lymphocytes that repeatedly stimulated by antigens?

Which pathway involves the activation of cytoplasmic adaptor proteins and procaspase-8?

Which receptor-ligand pair is most important in inducing apoptosis in T cells?

Where does central B-cell tolerance mainly occur?

What is the fate of mature B lymphocytes recognizing self antigens in peripheral tissues without T cell help?

What mechanism renders some B lymphocytes anergic or leads to their apoptosis when recognizing self antigens?

Which type of T lymphocytes function to control responses to self antigens in peripheral tissues?

What happens to some immature T cells in the thymus when they encounter self antigens?

In CD4+ T cells, what induces anergy?

"Receptor editing" may occur in B lymphocytes when:

"Peripheral tolerance" in B cells may involve each EXCEPT:

What mechanism causes mature CD4+ T cells to become unresponsive to an antigen?

Which signal is required for full activation of T cells?

What occurs in anergic cells that blocks TCR-induced signal transduction?

What happens when T cells recognize self antigens in the absence of innate immune responses?

Which of the following is NOT a mechanism that may function to induce and maintain the anergic state?

What is the result of self antigen recognition without costimulation?

What initiates the mitochondrial pathway of T cell deletion by apoptotic cell death?

Which proteins lead to increased mitochondrial permeability during T cell deletion?

What factor is crucial for the generation, survival, and functional competence of Regulatory T cells?

What activates cytosolic enzymes called caspases during T cell deletion?

What results from the insertion of BAX and BAK into the outer mitochondrial membrane during T cell deletion?

Which pathway of apoptosis is triggered by T lymphocytes recognizing antigens with high affinity or self?

What is the primary function of Regulatory T cells?

What type of stimuli can induce or activate cytoplasmic proteins of the BCL-2 family during T cell deletion?

Which transcription factor is expressed by CD4+ FOXP3+ CD25high T cells?

What cytokine is crucial for the survival and functional competence of Regulatory T cells?

In which tissues are the majority of Regulatory T cells thought to be derived from?

What is the most important death receptor in T cells involved in apoptosis induction?

Which cell surface receptors are engaged by their ligands in the extrinsic pathway of T cell deletion?

What is a homologous ligand to TNF in the context of T cell deletion?

Which mechanism may render mature B lymphocytes recognizing self antigens in peripheral tissues unresponsive?

What is the primary outcome when immature B lymphocytes recognize self antigens with high affinity in the bone marrow?

What process occurs when T cells encounter self antigens without additional stimuli or repetitive stimulation?

Which type of tolerance is induced in generative lymphoid organs when immature lymphocytes encounter self antigens?

What occurs when mature B lymphocytes recognize self antigens in the absence of specific helper T cells?

Which event leads to the activation of downstream caspases during apoptosis induction in T cells?

How are CD4+ T cells rendered anergic in the context of antigen recognition?

What is the primary effect of anergy on self-reactive T cells?

What is required for full activation of T cells?

What happens when T cells recognize self antigens in the absence of innate immune responses?

What is NOT a mechanism that may function to induce and maintain the anergic state?

Which cells are primarily responsible for actively suppressing the activation of lymphocytes specific for self and other antigens in peripheral tolerance?

What happens to TCR-associated proteins when self antigen recognition occurs without costimulation?

What is the term for the unresponsiveness to an antigen that is induced by exposure to that antigen?

What are the antigens that induce tolerance called?

What is the ability of the immune system to recognize and respond to foreign antigens but not to self antigens called?

What is the term for the phenomenon where some developing T and B cells in every individual may express receptors capable of recognizing normal molecules in that individual?

What is the term for the process of eliminating and inactivating lymphocytes that express high-affinity receptors for self antigens?

What is the term for the phenomenon where many self-reactive lymphocytes complete their maturation and are present in healthy individuals?

What is the term for the process of inducing self-tolerance in immature self-reactive lymphocytes in the generative lymphoid organs?

What is the term for the process of inducing self-tolerance in lymphocytes in peripheral or mature sites?

What is the term for the property of the normal immune system that prevents reactions to self antigens?

What is the term for the experimental observation that animals that had encountered an antigen under particular conditions would not respond to subsequent exposures to the same antigen?

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