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Flashcards in Autoimmunity Deck (63)
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1

What is the range of autoimmune disorders?

➝ systemic
➝ organ specific

2

What are 2 examples of an organ specific autoimmune disease?

➝ Graves disease
➝ Type 1 diabetes

3

What is Graves disease?

➝ an antibody response to the TSH receptors in the thyroid

4

Why do you get bulging eyes in Graves disease?

➝ Low level of TSH receptors in the fibroblasts in the eye
➝ immune deposition of antibodies in the eye

5

What are the 6 types of HLA B27- associated spondyloarthropathies?

➝ Ankylosing spondylitis
➝ undifferentiated spondyloarthropathy
➝ reactive arthritis
➝ psoriatic arthritis
➝ urethritis
➝ iritis

6

What is usually associated with HLA B27- associated spondyloarthropathy?

➝ bowel inflammation

7

What is the cause of systemic lupus erythematous (SLE)?

➝ Autoantibodies to nuclear antigens :
➝ double stranded DNA

8

What are the 8 signs of SLE?

➝ discoid lesions
➝ alopecia
➝ butterfly rash
➝ pericarditis
➝ arthritis
➝ proteinuria
➝Raynauds
➝ mucus membrane ulceration

9

What is autoimmunity?

➝ Failure of the regulatory controls in the immune system that prevent it attacking itself

10

What is central tolerance?

➝ Destroy self-reactive T or B cells before they enter the circulation

11

What is peripheral tolerance?

➝ Destroy or control any self reactive T or B cells which do enter the circulation

12

How does central tolerance of B cells occur?

➝ Immature B cells in bone marrow encounter an antigen in a form which can cross-link their IgM then apoptosis is triggered

13

What happens if a T cell binds to MHC too weakly?

➝ it may not be enough to allow signalling when foreign peptides are in the groove

14

What happens if a T cell binds to MHC too strongly?

➝ it may allow signalling irrespective of whether self or foreign peptide is in the groove

15

What types of T cells get selected in the thymus and which get destroyed?

➝ T cells that don't bind to any MHC - death by neglect
➝ T cells that bind to MHC too strongly - apoptosis triggered- negative selection
➝ T cells that bind self MHC weakly - signal to survive

16

How do T cells in the thymus encounter MHC bearing peptides from other parts of the body?

➝ A specialised transcription factor allows thymic expression of genes that are expressed in peripheral tissue

17

What is AIRE and what is its function?

➝ (autoimmune regulator)
➝ it promotes self tolerance by allowing the thymic expression of genes from other tissues

18

What do mutations in AIRE result in?

➝ multi organ autoimmunity

19

What are the three steps in peripheral tolerance?

➝ Ignorance
➝ anergy
➝ regulation

20

Why does the ignorance step happen in peripheral tolerance?

➝ the antigen may be present in too low a concentration to reach the threshold for T cell receptor triggering
➝ e.g immunologically privileged sites such as the eye or the brain
➝ T cells will not come across the antigen

21

What is anergy?

➝ Exposure to antigen without appropriate co-stimulatory signals

22

How does anergy occur?

➝ Naive T cells needs co-stimulatory signals to be activated
➝ most cells lack co-stimulatory proteins and MHC class II
➝ if a naive T cell sees its MHC/peptide without appropriate co-stimulation it becomes anergic

23

What does anergic mean?

➝ less likely to be stimulated in the future even if co-stimulation is present

24

What cells are involved in the regulation step in peripheral tolerance?

➝ Treg cells

25

How do Treg cells work?

➝ The Treg cells bind to an antigen on an APC they can send a negative signal to any other cells that are recognising antigens on that cell via TGF beta and IL-10

26

What two conditions cause a varying of Treg numbers?

➝ Cancer - increased Treg
➝ autoimmune - decreased Treg

27

What do Treg cells express?

➝ Transcription factor FOXP3

28

What do mutations in FOXP3 lead to?

➝ IPEX disease
➝ immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome

29

On what chromosome is MHC located?

➝ chromosome 6

30

How many genes are there for MHC class I and II?

➝ 3 for each