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Unit 3 Micro and Immunology > Autoimmunity > Flashcards

Autoimmunity Flashcards

1
Q

What are the 3 mechanisms that contribute to the development to autoimmune disease?

A

1- Defects in immunoregulation
2- Environmental triggers
3- genetic predisposition

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2
Q

What is an autoimmune disease?

A

“Self” antigen is recognized as foreign by immune system and there is a failure of regulatory mechanisms

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3
Q

What are the effector mechanisms of autoimmune disease?

A

Types II, III, or IV hypersensitivity reactions

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4
Q

What are the immune factors that contribute to autoimmune disease?

A

All autoimmune diseases involve the breakdown of T and B cell tolerance and the production of autoantibody and/or inflammatory autoreactive T cells

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5
Q

What are the genetic factors that contribute to autoimmune disease?

A

Genetic predisposition

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6
Q

Is a “trigger “ required to develop and autoimmune disease?

A

Yes– In the lab it is found that bacterial products are required to induce autoimmune response to injected self proteins

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7
Q

How does B cell tolerance breakdown?

A

No all reactive B cells are deleted during clonoal deletion in the boe marrow. As a result some autoreactive B cells remiain

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8
Q

How does T cell tolerance breakdown?

A
  1. Insufficient control of T cell co-stimulation (autoreactive T cells may have a lower threshold for activation)
    2-Lack of Regulatory T cells (Treg) may contribute to autoimmune disease
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9
Q

How does the T cell tolerance breakdown lead to problems with B cells?

A

Since there are autoreactive T cells around, these T cells can activate B cells. Therefore Autoreactive B cells can have T cell help when they normally would not

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10
Q

Can decreased production of T regs lead to autoimmune disease? If so why?

A

Yes it can.

These cells secrete IL-4, IL-10 and TGF-beta, and these levels are reduced with there is decreased T regs.

These factors are needed to suppress autoreactive cells

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11
Q

What is the role does defects in AIRE play?

A

when have defects you have many autoimmune responses

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12
Q

What is the phenotype of T regs?

A

CD4+, CD25+, CTLA-4+

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13
Q

Th-17 role?

A

Connect infection to autoimmune disease?

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14
Q

What to Th-17 cells do?

A

T help secrete IL-17

Pro-inflammatory-binds to IL-17 receptor on fibroblasts epithelial cells and keratinocytes, leading to secretion of cytokines and recruitment of inflammatory cells

May accumulate in affected tissues in Crohn’s disease, RA, psoriasis, allergic asthma

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15
Q

How are Th17 cells regulated?

A

Reciprocally regulted with Tregs

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16
Q

What are some examples of geneitc factors that contribute to autoimmune disease?

A

HLA- class II (in higher frequency in patients)

varients of CTLA-4

varients of AIRE

varients of Fas and Fas ligand

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17
Q

What is the role of fas and fas ligand?

A

to destroy autoractive cells

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18
Q

What are some hormonal factors contributing to autoimmune disease?

A

estrogen (lupus)

estrogen like chemicals

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19
Q

Role of release of sequestered antigens in autoimmune disease?

A

Trauma to sites of immune privilege – normally entry of naïve lymphocytes is prevented but self antigens may be exposed to circulation by wound or infection, and effector cells can gain access

20
Q

What is molecular minimcry? What is its significance?

A

Pathogen-derived peptides that are structurally similar to a self antigen.

These molecules can stimulate a T cell response direceted agains the self-antigen

21
Q

What is the role of Interferon gamma?

A

Upregulate MHC calss II expression of cells that normally do not express it during an infection.

These cells can then express self antigen when this happens

Example is hotchimoto’s diseas

22
Q

What are some environmental factors that lead to autoimmunity?

A

chemicals, loss of tolerance to food proteins, sunlight, aging, atrophy of thymus, nutrition, stree

23
Q

What are the characteristics of autoimmune disease?

A

may be classifiedas organ-specific if only one organ or cell type is involved

sometimes classified by the immunological effector mechanism causing disease

24
Q

Define antibody-mediated autoimmune diseases

A

a single type of cell (organ) is targeted by autoantbodies

this is an organ specific autoimmune disease

25
Q

What type of hypersensitivity reaction does antibody mediated autoimmune disease correlate to?

A

Type II hypersensitivity (antibody mediated)

26
Q

Please name some examples of antibody mediate autoimmune disease

A 
1- autoimmune hemolytic anemia
2- autoimmune thrombocytopenia
3- goodpasture's syndrome
4- Grave's disease
5- Insulin resistant diabetes
6- Myasthenia gravis
7- Hashimoto's disease
27
Q

Explain autoimmine hemolytic anemia

A

Loss of RBSs after fixation of compliment by IgG and IgM antibodies bound to components on RBCs

Lysis or phacocytosis results

28
Q

Explain autoimmune thrombocytopenia

A

platelet antigens are the targets of antibodies

29
Q

Explain goodpasture’s syndrome

A

IgG against Type IV collagen elicits an inflammatory response in renal tissues

30
Q

Explain grave’s disease

A

antibodies that bind to the TSH receptor act as an agonist, so that the thyroid hormones are overproduced

31
Q

Explain myasthenia gravis

A

antibodies to acetylcholamine receptors (AChR) on muscle cells unduce their endocytosis

antibodies also compete with acetylcholamine for binding to AChR. this results in progressive muscle weakening

32
Q

Explain insulin-resistant diabetes

A

insulin binding to receptor is blcked by antibody so that insuuling accumulates causing hyperglycemia. this is characterized by resistance to insulin

in patients with agonist antibodies, cells deplete glucose to abnormally low levels resulting in hypoglycemia

33
Q

Explain hashimoto’s disease

A

progressive destruction of normal thyroid tissue by antibodies and effector T cells, leading to hypothyroidism

34
Q

What is mainly effected by antibody-mediated autoimmune diseases?

A

endocrine glands

35
Q

Describe immune-complex-mediated autoimmune diseases

A

autoimmune response is directed at multiple cells of teh body, resulting in a systemic autoimmune response

36
Q

What type of hypersensitivity reaction does immune-complex mediated autoimmune disease correlate to?

A

Type III Hypersensitivity

37
Q

What is an example of immune-complex mediated autoimmune diseases?

A

Systemic lups Erythematosus

38
Q

Explain SLE (immune complex mediated and T cell mediated):

A

Circulating antibodies that are specific for the constituents of cell surfaces, cytoplasm, and the nucleus indluding nucleic acids

autoantibodies and autoantigens form immune complexes that are deposited in he blood vessels, kidneys, and joints and initiate inflammatory reactions

There is also a T cell component

39
Q

What is diagnostic of SLE?

A

antibodies to dsDNA

40
Q

Describe T-cell mediated autoimmune diseases:

A

antigens in tissue are targeted by Th1- type T cells

41
Q

What type of hypersensitivity reaction does T-cell mediated autoimmune disease correlate to?

A

Type IV hypersensitivity

42
Q

What are examples of T-cell mediated autoimmune disease?

A

Insulin-dependent diabetes mellitus
rheumatoid arthritis
multiple sclerosis
SLE

43
Q

Explain IDDM:

A

CD8+ T cells are cytotoxic to pancreatic beta cells so that insulin so tht insulin production is in sufficient to control glucose levels in the blood

44
Q

Explain RA

A

Rheumatoid factors and cellular infiltrate contribute to inflammation in the joints

45
Q

What are rheumatoid factors?

A

RF-IgM, IgG, and IgA antibodies specific for the Fc region of human IgG

46
Q

What are cellular infiltrates?

A

CD4+, CD8+ T cells

47
Q

Explain multiple sclerosis

A

anutoimmune resonse to antigens in the myelin sheath of nerve cells, involving Th1 CD4+ Tcells and macrophages

sclerotic plaques result and there is typically progressive paralysis

Unit 3 Micro and Immunology (25 decks)

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