Immunotolerance

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What does immunotolerance mean?

The activation of immune responses to all encountered antigens
A state of non-reactivity to an antigen after prior exposure (correct)
The immediate destruction of foreign antigens by immune cells
Permanent immunity tot all pathogens after initial exposure

Which of the following differentiates central and peripheral tolerance?

Central tolerance occurs in lymph nodes, while peripheral tolerance occurs in spleen
Central tolerance involves mature cells, while peripheral tolerance involves immature cells
Central tolerance eliminates self-reactive lymphocytes in primary organs, whereas peripheral tolerance regulates lymphocytes in tissues (correct)
Both central and peripheral tolerance occur exclusively in the thymus

What is the role of positive selection in the thymus?

To ensure that only T-cells that recognize self antigens survive
To ensure that T cells that recognize self-MHC molecules survive (correct)
To eliminate self-reactive T cells
To generate antibodies against self antigens

Why is negative selection critical for immune function?

It ensures the elimination of T cells that might react against self antigens (B) Signup and view all the answers

What is the function of the AIRE protein in the thymus?

It regulates peripheral tissue antigens, aiding in T cell self-tolerance (B) Signup and view all the answers

How does the induction of tolerance differ between T cells and B cells?

T cell tolerance includes Treg formation; B cell tolerance includes receptor editing (C) Signup and view all the answers

What is the primary function of regulatory T (Treg) cells?

They suppress self-reactive immune responses to prevent autoimmunity (B) Signup and view all the answers

Which cytokines are essential for the survival and function of Treg cells?

IL-2, IL-10, and TGF-β (A) Signup and view all the answers

Which other organs/systems play a role in modulation immune responses?

The endocrine and nervous systems, by balancing immune activation (B) Signup and view all the answers

Which mechanism contributes to peripheral T cell tolerance by rendering T cells functionally unresponsive?

Anergy (D) Signup and view all the answers

Which condition typically leads to T cell anergy in peripheral tolerance?

Recognition of self-antigens in the absence of costimulation or innate immune signals (A) Signup and view all the answers

How do regulatory T cells (Tregs) contribute to peripheral tolerance?

By suppressing immune responses through the release of immunosuppressive cytokines such as IL-10 and TGF-β (C) Signup and view all the answers

What cytokine is crucial for the survival and functional maintenance of regulatory T cells (Tregs)?

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

What role does the inhibitory receptor CTLA-4 play in T cell regulation?

CTLA-4 blocks the B7 molecule on antigen-presenting cells (APCs), reducing activation signals for T cells (A) Signup and view all the answers

Which ligands interact with the PD-1 inhibitory receptor to down regulate T cell response?

PD-L1 and PD-L2 (B) Signup and view all the answers

What is the result of PD-1 interaction with its ligands on T cells?

Inhibition of T cell signaling and reduced immune response (B) Signup and view all the answers

What causes Autoimmune Polyendocrine Syndrome Type 1 (APS1)?

A mutation or failure of the Autoimmune Regulator (AIRE) protein (C) Signup and view all the answers

What is a characteristic outcome of APS1 due to defective AIRE protein activity?

Autoimmune attacks on multiple endocrine organs (C) Signup and view all the answers

In APS1, why are multiple endocrine organs affected?

The failure of AIRE limits the presentation of peripheral antigens, leading to self-reactive T cells escaping tolerance mechanisms (B) Signup and view all the answers

Immunotolerance definition

A state where the immune system doesn't react to a specific antigen.

Central vs. Peripheral Tolerance

Central tolerance happens in the primary organs (thymus and bone marrow), while peripheral tolerance happens in the tissues.