Immunology - Hypersensitivity

Question 1

T1 hypersensitivity
Describe it?
Which Ig is it mediated by?
What happens?

Answer 1

Anaphylaxis
IgE mediated
IgE binds to basophils and mast cells - degranulation= histamine
Histamine cause vasodilation + increased permeability (H1 receptor), bronchoconstriction, facial flush
Eg. Atopy,- asthma, hey fever, rhinitis, ecsma

Question 2

T2 hypersensitivity
Describe it?
Which Ig is it mediated by?
What happens?

Answer 2

Antigen - antibody complex
Ig G & M binds to antigen and activates MAC (complement) AT SITE OF A-A BINDING
Eg. Good pastures, AIHA, pernicious anaemia, rheumatic fever

Question 3

T3 hypersensitivity
Describe it?
Which Ig is it mediated by?
What happens?

Answer 3

Immune complex deposition
Ig G/A binds to antigen + activates complement at SITE OF A-A DEPOSITION (kidneys =big boy affected)
Eg, SLE (systemic lupus erythmatosis), post strep glomerulonephritis, IgA glmerulonephritis

Question 4

T4 hypersensitivity
Describe it?
Which Ig is it mediated by?
What happens?

Answer 4

T cell mediated
Th1 activated by APCs = response
Eg. T1DM, MS, TB, Guillain barre

Question 5

T5 hypersensitivity
Describe it?
Which Ig is it mediated by?
What happens?
(Extra)

Answer 5

Ig G/M binds to CSR and prevents/stimulates endogenous ligand action)
Eg. Graves,