Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Autoimmune > 3 . Mechanisms > Flashcards

3 . Mechanisms Flashcards

1
Q

What is lost by self-antigens in AI’s?

A

Tolerance to self-antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does the immune system respond to self-tissues in healthy individuals?

A

It is tolerant of self-tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are chronic adaptive immune responses directed to in AI disease?

A

Towards normal body components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can happen to cells and tissues in AI disease?

A

Can be destroyed or have function altered.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the role of self-antigens? (autoantigen)

A

Antigenic component/amino acid sequence that provokes immune response by individuals OWN system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an antigens role?

A

Molecules or molecular fragments that can be bound by an MHC molecule and presented to a T-cell receptor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What humoral mechanisms can be involved in inappropriate AI response to self -antigens?

A

Humoral mechanisms via B-cells and antibodies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What cell-mediated mechanisms can be involved in inappropriate AI response to self -antigens?

A

Via T-cells and cytokines.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do T-cells function?

A

Diverse and interact with antigen often dictates fate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What chain does a T-cell follow?

A

T-cell maturation. T lymphocyte activation. Clonal expansion into helper/memory/suppressor- T cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Steps of B cell function?

A

.Immunoglobulins on B cell surface attach to antigen.
.Fragment of antigen in B cell combines with HLA II.
.HLA II antigen-fragment-complex on surface of B cell.
.TH Cell receptor recognizes HLA complex. Cytokines activate B cell.
.Clonal expansion begins. Some become antibody producing plasma cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When was ‘Tolerance’ defined?

A

1953 by Medawar and Burnet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define ‘Tolerance’?

A

“A state of indifference or non-reactivity towards a substance that would normally be expected to excite an immunological response.”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does tolerance do?

A

Helps fight and ensure NO ai disease develops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do we develop ability to tolerate self-antigens?

A

From exposure of self-antigens to autologous lymphocytes in early development (self)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens if tolerance fails?

A

Failure to tolerate self-antigens can trigger ai development.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is Central Tolerance?

A

Regulation of B and T cells that proliferate in thymus and BM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does central tolerance impact B and T cells in thymus/bm?

A

Makes them unreactive to self-antigens. Originally they are reactive but regulatory processes nullify this later on.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do T-cell receptors gene rearrangements cause in immature T cells?

A

Randomly generate thousands of antigen specific TCRs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does the thymus do in central tolerance?

A

Selects and eliminates auto-reactive T-cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When does thymus select and eliminate autoreactive T Cells?

A

Early in life. Near heart.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the thymus POSITIVELY select in central tolerance?

A

Tcells with TCRs that bind to MHC associated antigens expressed by epithelial thymocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the thymus NEGATIVELY select in central tolerance?

A

Negatively selects and induces apoptosis in TCells with high avidity for self-antigens on epithelial thymocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do thymus macrophages phagocytose in central tolerance?

A

Apoptotic dead T-cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What percentages of Tcells die in central tolerance?

A

98% due to being autoreactive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where are thymocytes found?

A

Distinct parts of the thymus depending on stage of development.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

List mechanism of central tolerance thymocytes in TCells?

A

.Cells enter thymus into subcapsular region of cortex.
.Proliferate and mature into double positive thymocytes.
.Migrate deep in thymic cortex.
.Medulla left with MATURE SINGLE POSITIVE T CELLS.
.Leave thymus and enter blood

28
Q

Name the 2 ways ai TCells can be activated in central tolerance?

A

In a pathogen specific or non-specific manner

29
Q

How are ai T cells pathogen-specifically activated by infection?

A

Specific pathogen antigens presented to T-cells via TCR and MHC interaction

30
Q

How are ai T Cells activated in a non-specific manner?

A

Inflammation or reduced regulation by cytokines

31
Q

What can Inappropriate class II MHC expression activate in central tolerance?

A

B or Cytotoxic T Cells

32
Q

Examples of Inappropriate class II MHC expression in central tolerance?

A

Pancreatic B Cells express high Class II MHC in diabetes. Thyroid cells express high CLASS II MHC in Graves disease.

33
Q

What can viruses promotes in central tolerance that increases class II MHC expression by cells that should not express it?

A

Viruses promote Interferon-g release by T-cells.

34
Q

When are the majority of B cells clones generated and how?

A

During foetal development. Randomly generated by gene rearrangements. Many are autoreactive and tolerance eliminated.

35
Q

Where do developing B Cells undergo +ive/-ive selection?

A

In Bone marrow an germinal centres of other lymphoid tissues. (most undergo apopotosis)

36
Q

What enables Bcells to produce heavy and light chai immunoglobulin receptors and functional BCR?

A

Induction of RAG initiates VDJ recombination.

37
Q

What are immature B cells subjected to in CT?

A

subjected to central tolerance mechanisms that eradicate autoreactive cells

38
Q

What happens to B cells that express BCRs that bind self-antigen ?

A

Undergo receptor editing in an attempt to produce BCRs that are not autoreactive.

39
Q

What happens to B cells that successfully pass these central tolerance checkpoints?

A

Leave the bone marrow and travel to the spleen where they are subjected to further tolerance mechanisms

40
Q

Where do autoreactive B Cells migrate to when stimulated by autoantigen?

A

T cell area of secondary lymphoid tissues.

41
Q

What is the effect between B and T cells in CT?

A

T cells allow B cells to survive and cause disease. Without they will die.

42
Q

What virus can induce non-specific polyclonal BCell activation?

A

Epstein Barr and Cytomegalovirus

43
Q

How do viruses and bacteria impact BCells?

A

Bcells produce IgM which combines with IgG to = immune complexes.

44
Q

What is AIRE?

A

Autoimmune Regulator. Transcription factor.

45
Q

What does AIRE do?

A

Promotes the ectopic transcriptional activity of a large number of chromosomal locations, thereby enhancing the expression by medullary epithelial cells (MECs) of genes that would normally only be expressed in specific tissues

46
Q

Where is AIRE localised?

A

Thymus- medulla

47
Q

What is AIRE involved in?

A

Negative selection

48
Q

What is meant for AIRE by ‘immunological shadow’

A

Shadow of the peripheral self in MECs.

49
Q

What happens to AIRE with differentiating T cells that recognize these antigens?

A

Removed primarily by apoptotic clonal deletion, although some may survive by adopting alternative fates that have regulatory rather than autoreactive properties.

50
Q

What does the regulatory element of AIRE achieve?

A

These mechanisms thus prevent the autoimmune attack of peripheral organs.

51
Q

What disease is AIRE linked to?

A

Autoimmune Polyendocrinopathy Syndrome
Type I

52
Q

What is Autoimmune Polyendocrinopathy Syndrome
Type I?

A

Dysfunction of multiple endocrine glands.

53
Q

What causes Autoimmune Polyendocrinopathy Syndrome
Type I?

A

AIRE gene mutations

54
Q

Impact of Autoimmune Polyendocrinopathy Syndrome
Type I?

A

Tolerance less. Persistant mucosal fungal infections.

55
Q

What gland does Autoimmune Polyendocrinopathy Syndrome Type I effect?

A

Parathyroid and adrenal.

56
Q

What is FOXp3?

A

Forkhead box p3. Regulator master for T-Cell regulation. Transcriptional regulator. Essential for development and function.

57
Q

What does FOXp3 do?

A

Predominantly acts to directly supress activation of target genes.

58
Q

What phenotype isFOXp3 comitted to?

A

Treg phenotype from precursor cells.

59
Q

Explain the regulatory elements of Tregs?

A

A regulatory T Cell that expresses CD4/CD25 and FOXp3/
.

60
Q

What is FOXp3 essential for?

A

Immune supression

61
Q

What does FOXp3 mutations cause?

A

Disease IPEX

62
Q

What is supressed in FOXp3?

A

Activation/proliferation and cytokine production in CD4/CD8 TCells.

63
Q

What is peripheral toleracne?

A

A redundancy mechanism within the immune system. Regulates cells in peripheral tissue and limits access to tissues when activated.

64
Q

What circulates in peripheral tolerance?

A

Self-reactive B and T cells that survive toleracne

65
Q

Define peripheral tolerance?

A

Tolerance to self antigens acquired by lymphocyte population outside thymus and BM .

66
Q

What regulates peripheral tolerance?

A

CTLA-4. HLA-B7 co stimulator on APC membrane.

67
Q

What supresses peripheral tolerance?

A

Autoimmune (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions