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Immunology > Regulation of immunity 2 > Flashcards

Regulation of immunity 2 Flashcards

1
Q

What is immune tolerance?

A

A state of unresponsiveness of the immune system to specific antigens, immune tolerance usually occurs to prevent immune attacks against self-tissues

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2
Q

What are the two main types of immune tolerance?

A

Central tolerance and peripheral tolerance

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3
Q

Where does central tolerance occur for T cells?

A

In the thymus during T cell development

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4
Q

Where does central tolerance occur for B cells?

A

In the bone marrow during B cell development

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5
Q

What is the role of AIRE in central tolerance for T cells?

A

AIRE facilitates the expression of peripheral tissue antigens in the thymus for negative selection of self-reactive T cells

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6
Q

What is clonal deletion in central tolerance?

A

The process where self-reactive T or B cells are eliminated through apoptosis during development

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7
Q

What is receptor editing in central tolerance for B cells?

A

A mechanism where B cells rearrange their immunoglobulin genes to generate a new non-self-reactive B cell receptor

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8
Q

What is clonal anergy?

A

A state of functional unresponsiveness in T or B cells that recognize self-antigens without co-stimulatory signals

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9
Q

What is clonal ignorance?

A

When self-reactive T or B cells ignore antigens in immune-privileged sites such as the brain or the eye

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10
Q

What is peripheral tolerance?

A

Mechanisms that regulate immune responses to self-antigens in peripheral tissues

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11
Q

What are T regulatory cells (Tregs)?

A

CD4+ T cells that suppress immune responses and maintain self-tolerance

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12
Q

What are the two main types of Tregs?

A

Thymus-derived Tregs (nTregs) and peripheral-induced Tregs (pTregs or iTregs)

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13
Q

What cytokines are critical for Treg function?

A

TGF-beta and IL-10

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14
Q

How do Tregs suppress immune responses?

A

Through secretion of suppressive cytokines like IL-10 and TGF-beta and by directly interacting with antigen-presenting cells and effector T cells

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15
Q

What is activation-induced cell death (AICD)?

A

A process where persistent antigen exposure induces apoptosis in activated T cells through Fas-FasL interactions

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16
Q

What is immune deviation?

A

A mechanism where the immune system shifts responses to reduce tissue damage, such as shifting from Th1 to Th2 responses

17
Q

How does the CTLA-4 receptor regulate T cell activation?

A

CTLA-4 competes with CD28 for B7 ligands on APCs to deliver inhibitory signals to T cells

18
Q

What is the role of PD-1 in immune regulation?

A

PD-1 inhibits signals from TCR and CD28 in already activated T cells to limit immune responses

19
Q

What is the function of inhibitory receptors like CD22 and FcγRIIb on B cells?

A

They dampen activation signals to prevent inappropriate responses to self-antigens

20
Q

What is the role of IL-2 in Tregs?

A

IL-2 is required for the differentiation, survival, and functional competence of Tregs

21
Q

What happens when self-reactive T or B cells encounter antigens in immune-privileged sites?

A

They are either ignored, suppressed by inhibitory molecules, or undergo apoptosis

22
Q

What are some diseases caused by failed central tolerance?

A

APECED (T cell failure due to AIRE mutation) and SLE (B cell failure in receptor editing)

23
Q

What are some diseases caused by failed peripheral tolerance?

A

IPEX syndrome (defective Tregs due to FOXP3 mutation) and rheumatoid arthritis (failure of B cell anergy)

24
Q

What are the therapeutic applications of immune tolerance mechanisms?

A

Autoimmune disease treatments, cancer immunotherapy, and transplantation tolerance

25
Q

What are the key cytokines for maintaining immune homeostasis?

A

IL-10 and TGF-beta

26
Q

How does chronic weak signaling lead to B cell anergy?

A

Chronic signaling without co-stimulatory signals reduces IgM expression and impairs BCR signaling, leading to apoptosis

27
Q

How do inhibitory receptors like PD-1 and CTLA-4 contribute to tolerance?

A

They block T cell activation and maintain immune regulation by preventing overactivation

28
Q

What is the role of TGF-beta in inflammation and tolerance?

A

It induces Tregs and regulates inflammation by suppressing Th1 and Th2 responses while promoting Th17 differentiation during infection

Immunology (25 decks)

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