Hypersensitivity and Autoimmunity

Question 1

Type I hypersensitivity

Answer 1

Where the body recognises an environmental antigen as a pathogen and releases IgE and triggers mast cell response

during sensitisation, the allergen is shown to a T helper cell by an APC
causes B cells to differentiate to produce IgE against the antigen

exposer to the antigen will cause the release of cytokines from mast cells, resulting in an allergic response

Question 2

Type II hypersensitivity

Answer 2

the body’s antibodies bind to the antigens on its own cell surface

antibodies are produced in response to the antigens on the cell surface eg. when penicillin binds to blood cells

IgG and IgM antibodies trigger the complement system causing cell lysis

Question 3

Type III hypersensitivity

Answer 3

Characterised by the formation of immune complexes

a low conc. of antibodies couples with a large conc. of antigen causes small complexes to form

Question 4

Type IV hypersensitivity

Answer 4

the body’s CD4 helper T cells recognise the foreign antigen and starts to produce cytokines which leads to an inflammatory response

Question 5

pathophysiology of early phase recognition

Answer 5

occurs within minutes

performed mast cell mediators (histamine, heparin, chemotactic factors)

Question 6

pathophysiology of late phase response

Answer 6

newly synthesised mediators (prostaglandins, leukotrienes)

Th2 cytokines

Eosinophil mediators

Question 7

the pathophysiology of immune complexes formation in localised and systemic type III hypersensitivity

Answer 7

localised- causes localised inflammation and can be cleared away by macrophages

systemic- complexes are deposited in tissue and organs such as the skin, joints, kidneys and blood vessels

Question 8

what is an autoimmune disease

Answer 8

A large group of clinical disorders characterised by tissue or organ damage mediated by incorrect immune mechanisms targeted at self-antigens

Question 9

factors involved in the aetiology of autoimmune disease

Answer 9

genetic factors

immune regulatory factors

hormonal factors

environmental factors

Question 10

Pathogenic mechanisms involved in autoimmune disease

Answer 10

cell-mediated

antibody-mediated

antibody + complemented

immune complex-mediated

recruitment of innate compounds

Question 11

organ specific autoimmune disease

Answer 11

thyroid, stomach, adrenal