Hypersensitivity Reactions

Question 1

Describe the types of hypersensitivity reactions that can lead to tissue damage

Answer 1

Type 1 e.g. anaphylaxis, urticaria, hay fever, asthma - immediate, IgE –> mast cell activation
Type 2 e.g. Graves’ disease, myasthenia gravis, pernicious anaemia, Goodpasteur’s syndrome - antibody mediated, IgG or IgM –> complement –> opsonisation, cell death, chemotaxis
Type 3 e.g. RA, glomerulonephritis, SLE - immune complexes mediated, IgG and IgM (tissue damage due to deposition)
Type 4 e.g. TB, leprosy, schistosomiasis, sarcoidosis, DM, Hashimoto’s disease, Coeliac disease - cell mediated, TH1/2, cytotoxic T lymph

Question 2

Define the term ‘autoimmune disease’

Answer 2

Immune response against self antigens/pathogens that leads to tissue damage or disturbed psychological function

Question 3

Explain the pathophysiology of Goodpasteur’s syndrome

Answer 3

Anti basement membrane –> glomerulonephritis, lung haemorrhage
IgG deposition

Question 4

Describe the mechanism of rhesus

Answer 4

Rhesus -ve mother
2nd Rh+ve foetus
Antibodies attack foetus

Question 5

List therapeutic options of autoimmune diseases

Answer 5

Replacement of function
Immunosuppression
Monoclonal antibodies
High doses of IV Ig
Splenectomy

Question 6

Explain plasmapheresis in the management of certain antibody-mediated hypersensitivity

Answer 6

Short term relief
Allows healing of damaged tissue
6-8 times in two weeks
1-3hrs duration

Question 7

Define the term ‘hypersensitivity reaction’

Answer 7

The antigen specific immune responses that are either inappropriate or excessive and result in harm to host