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Year 3: CSP & PH > HLA > Flashcards

Flashcards in HLA Deck (43)
1

What is MHC?

the cluster of genes that encode the molecules involved in antigen presentation

2

What are the different types of HLA molecules?

> Class I = HLA-A, HLA-B, HLA-C
> Class II = HLA-DP, HLA-DQ and HLA-DR

3

What is the function of HLA Class I?

Endogenous antigen is presented to CD8+ T cells (T killer cells)

4

What is the function of HLA Class II?

Exogenous antigen is presented to CD4+ (helper) T cells (helps production of antibodies by B cells)

5

What is meant by 'linkage disequilibrium'?

the occurrence in members of a population of combinations of linked genes in non-random proportion

6

Describe clonal deletion of B lymphocytes

• If the B cell is immature in the bone marrow (only express IgM, not IgD as well) when exposed to an antigen it will die
• When B cells are undergoing expansion and mutation (clonal expansion) in the bone marrow and fail to get help from CD4 (helper) T cells, then then they will die

7

Describe clonal deletion of T lymphocytes

• Central tolerance – as T cells develop in the thymus (and B cells in the bone marrow) their receptors are tested for reactivity to self-antigens. If there reactivity is too strong, the lymphocytes are killed.
• Peripheral tolerance – self-reactive lymphocytes that escape deletion during development can be controlled in the periphery by T regulatory cells.

8

What is an 'autograft'?

graft of tissue given back to the same person

9

What is an 'isograft'?

graft between two identical siblings

10

What is an 'allograft'?

graft between two members of the same species

11

What is a 'heterograft/xenograft'?

graft between two different species

12

What is hyperacute rejection?

Immediate rejection due to presence of pre-formed antibodies. Presents with thrombosis and occlusion of graft vessels

13

What is acute rejection?

Takes weeks to months and involved T-cell mediated response against the foreign HLA

14

What is chronic rejection?

Takes months to years. Involves T cell responses and antibodies to non-self antigen

15

How can you prevent rejection in organ transplantation?

Match donor and recipient HLA, use anti-rejection therapy, be aware of previous exposure to forei

16

Describe type 1 hypersensitivity

IgE mediated release of histamine from mast cells/basophils e.g. asthma, hay fever, anaphylactic shock

17

Describe type 2 hypersensitivity

IgG and IgM-mediated destruction by complement and/or phagocytosis

18

Describe type 3 hypersensitivity

Immune complexes causing pathology where they are formed or where they are deposited

19

Describe type 4 hypersensitivity

Mediated by activated T cells with or without granulomas

20

Describe type 5 hypersensitivity

mediated by antibodies that stimulate rather than destroy their target

21

Give examples of type 1 hypersensitivity

hayfever, asthma, anaphylactic shock

22

Give examples of type 2 hypersensitivity

antibody-mediated haemolytic anaemia, thrombocytopenia, myasthenia gravis, Goodpastures, pemphigus and pemphigoid

23

Give examples of type 3 hypersensitivity

Where they are formed = extrinsic allergic alveolitis etc.
Where they are deposited = vasculitis, glomerulonephritis, arthritis etc.

24

Give examples of type 4 hypersensitivity

TB, hepatitis B, coeliac

25

Give examples of type 5 hypersensitivity

Graves’ disease (autoimmune)

26

What is HLA B27 associated with?

ankylosing spondylitis, reactive arthritis, colitic arthritis, psoriatic arthritis

27

What are HLA DQ2 and DQ8 associated with?

Coeliac disease and T1DM

28

What is Cw6 associated with?

Psoriasis

29

What is HLA DQ6 associated with?

MS

30

What is HLA DR4 associated with?

Rheumatoid arthritis

31

What is HLA DR3 associated with?

Graves' disease, myasthenis gravis

32

What is myasthenia gravis?

Autoantibody against ACh receptor muscle weakness, diplopia, respiratory paralysis

33

What is Eaton-Lambert syndrome?

autoantbody to presynaptic Ca2+ channels at the NMJ muscle weakness

34

What cancer does Eaton-Lambert syndrome increase the risk of ?

Small cell carcinoma of the lung

35

What is pemphigus?

skin disease with autoantibodies to desmosomes bullae form within the epidermis and form sores on the skin and mouth ulcers

36

What is pemphigoid?

skin disease with autoantibodies to hemidesmosomes stable bullae form which are less likely to break down that in pemphigus

37

What is Goodpasture's syndrome?

autoantibodies to type IV collagen in basement membranes glomerulonephritis

38

What is Hashimoto's thyroiditis?

Hypothyroidism; autoantibodies to TPO and anti-thyroglobulin but most damage is done by T cells

39

What is pernicious anaemia?

Autoantibodies against parietal cells or anti-intrinsic factor anitbodies present no absorption of B12 and achlorhydria increases risk of gastric cancer

40

What cancer does pernicious anaemia increase your risk of developing?

Gastric cancer

41

Describe chronic autoimmune hepatitis

Affects young women, autoantibodies can include ANA, anti-SMA

42

What autoantibodies may be present in primary biliary sclerosis?

Anti-ANA may be positive as well as anti-mitochondrial antibodies

43

What autoantibodies may be present in primary sclerosing cholangitis?

Associated with UC, usually ANCA positive