Hypersensitivity and autoimmunity Flashcards

1
Q

What is an autoimmune disease?

A

A failure or break down of the immune system which maintains tolerance to self tissues

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2
Q

Provide examples of different ways to treat autoimmune disease

A
Blanket immunosuppression(can lead to infection)
Target selective approach9target the aberrant immune activation whilst leaving the rest of the immune system intact)
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3
Q

Define hypersensitivity

A

Hyper response from immune system

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4
Q

How many types of hypersensitivity are there?

A

4

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5
Q

Describe type 1 hypersensitivity

A
  • IgE
  • Soluble antigen(allergen)
  • Allergy

(• This is where the body recognises an environmental antigen as a pathogen and releases IgE and triggers Mast cell responses.
• During sensitisation, the allergen is shown to a T helper cell by an APC. This causes B cells to differentiate to produce IgE against the antigen.
• From then onwards, exposure to the antigen will cause the release of cytokines from Mast cells, resulting in an allergic response. )

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6
Q

Describe type 2 hypersensitivity

A
  • IgG
  • Cell or matrix antigen
  • AIHA or rhematic fever

(• In this type, the body’s antibodies bind to the antigens on its own cell surfaces.
• Antibodies are produced in response to the antigens on the cell surfaces e.g. when penicillin binds to blood cells
• IgG and IgM antibodies trigger the complement system causing cell lysis)

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7
Q

Describe type 3 sensitivity

A

-IgG
-Soluble antigen
-SLE
-Arthritis
(• This form of hypersensitivity is characterised by the formation of immune complexes (clumps of antibodies that have stuck together)
• A low conc. of antibody coupled with a large conc. of antigen causes small complexes to form)

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8
Q

Describe type 4 sensitivity

A
  • Th1, Th2, CTL
  • soluble antigen, cell
  • antigen,inf-gamma
    Type 1 diabetes
    (• The body’s CD4 helper T cells recognise the foreign antigen, and starts to produce cytokines which leads to an inflammatory response. )
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9
Q

Describe central tolerance

A

The process of eliminating lymphocytes that are self reactive

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10
Q

Describe peripheral tolerance

A

The process of eliminating T cells which avoided central tolerance

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11
Q

What type of lymphocytes acquire peripheral tolerance?

A

Mature lymphocytes in the peripheral tissue

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12
Q

What type of lymphocytes acquire central tolerance

A

Immature lymphocytes during their development

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13
Q

How may self reactive lymphocytes escape negative selection?

A

due to low affinity to self MHC/antigen and the exclusive expression of some proteins in the periphery

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14
Q

Name some factors which affect auto-immune diseases?

A

genetic predispositions
Hormonal/sex
Environmental co-factors
immunity regulatory factors

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15
Q

Describe systemic autoimunne disease

A

Systemic

Autoimmune process is spread throughout the body - affects more than one organ. eg systemic lupus erythematosus (SLE)

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16
Q

Describe organ specific autoimmune disease

A

Autoimmune process directed against one organ. eg type 1 diabetes

17
Q

What type of hypersensitivity is SLE

A

type 4

18
Q

What type of hypersensitivity is diabetes mellitus

A

type 4

19
Q

What type of hypersensitivity is arthritis

A

Type 3

20
Q

Compare early and late phase responses

A

Early phase response
-occurs within minutes
-preformed mast cells mediators(histamin, heparin, chemotactic factors)
Late phase response
-New synthesised mediators (prosaglandins,leukotrienes)
-Th2 cytokins
Eosinophil mediators