13 Immune Tolerance Flashcards Preview

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Flashcards in 13 Immune Tolerance Deck (34):
1

Unresponsiveness to an antigen is induced by previous exposure to that antigen

Immunological tolerance

2

Antigens that induce tolerance

Tolerogens

3

Antigens that produce immune responses

Immunogenic

4

Antigen-specific lymphocytes may not reach in any way
Lymphocytes simply ignore the presence of the antigen

Immunological ignorance

5

Tolerance to self-antigens

Self tolerance

6

Treatment of disease using therapeutic agents that promote immune response

Immunotherapy

7

Substances that enhance T cell activation by promoting the accumulation of APCs at a site of antigen exposure and enhancing costimulators and cytokines by the APC

Adjuvants

8

Preparation of microbial antigen, often combined with adjuvants, administered to individuals to induce protective immunity against microbial infection

Vaccine

9

Induced when immature lymphocytes encounter self antigens in the generative lymphoid organs

Central tolerance

10

Mature lymphocytes encounter self antigens in secondary lymphoid organs or peripheral tissue

Peripheral tolerance

11

Two factors affecting T cell tolerance

Concentration of antigen in thymus
Affinity of thymocyte to recognize antigen

12

Immature lymphocytes interact strongly with a self antigen, displayed as a peptide bound to MHC
Receives signals that trigger apoptosis, and the cell dies before it can complete its maturation

Negative selection

13

Immature helper T cells that recognize self antigens in the thymus with high affinity do not die but develop into regulatory T cells and enter peripheral tissues

Development of CD4 regulatory T cells

14

Induced when mature T cells recognize self antigens in peripheral tissues, leading to functional inactivation, or when the self-reactive lymphocytes are suppressed by regulatory T cells

Peripheral T lymphocyte tolerance

15

Functional unresponsiveness
Occurs when cells recognize antigens without adequate levels of costimulators for full T-cell activation

Anergy

16

Subset of CD4 T cells
Function to suppress immune response
Maintain self tolerance

Regulatory T cells

17

Secreted by regulatory T cells
Responsible for maintaining some form of suppression
Can act on mast cell, eosinophils, B cells and T cells

IL-10

18

Development and function of regulatory T cells are dependent on transcription factor

FoxP3

19

Clonal deletion pathways

Extrinsic
Intrinsic

20

Via death receptor that culminates in the activation of caspases and apoptosis by the death receptor pathway

Extrinsic pathway

21

Via mitochondrial pathway to induce apoptosis

Intrinsic pathway

22

Immune complex mediated hypersensitivity that involves skin and mucous membrane

Steve Johnson Syndrome

23

Thymus-dependent self antigens

Proteins

24

Thymus-independent self antigens

Polysaccharides and lipids

25

Occurs in the bone marrow where immature B cells are found
Recognition of B cells that have high affinity to self antigen

Central B lymphocyte tolerance

26

Mechanisms of central B lymphocyte tolerance

Clonal deletion
B cell receptor editing

27

Cellular death
If self antigens are recognized with low affinity, B cells become anergic
If editing fails, they receive death signals and undergo apoptosis

Clone deletion

28

Reexpression of genes that resume Ig light chain recombination to produce new light chain

B cell receptor editing

29

Occurs in the spleen and lymph nodes where mature B cells can be found

Peripheral B lymphocyte tolerance

30

Mechanisms of peripheral B lymphocytes tolerance

Anergy
Follicular exclusion
Apoptosis

31

Reduction of B cells survival when they are able to recognize self antigens

Anergy

32

B cells are unable to enter the follicles due to changes in survival signals that blocks its migration

Follicular exclusion

33

Cell death

Apoptosis

34

Expressed after T cell activation and antigen elimination
Inhibits continued lymphocyte proliferation
Physiologic terminator of T cell activation

CTLA-4 and PD1