The Gell and Coombs classification divides hypersensitivity traditionally divides reactions into 4 types:
| Type | Mechanism | Examples |
|---|---|---|
| Type I - Anaphylactic | Antigen reacts with IgE bound to mast cells | • Anaphylaxis |
| • Atopy (e.g. asthma, eczema and hayfever) | ||
| Type II - Cell bound | IgG or IgM binds to antigen on cell surface | • Autoimmune haemolytic anaemia |
| • ITP | ||
| • Goodpasture's syndrome | ||
| • Pernicious anaemia | ||
| • Acute haemolytic transfusion reactions | ||
| • Rheumatic fever | ||
| • Pemphigus vulgaris / bullous pemphigoid | ||
| Type III - Immune complex | Free antigen and antibody (IgG, IgA) combine | • Serum sickness |
| • Systemic lupus erythematosus | ||
| • Post-streptococcal glomerulonephritis | ||
| • Hypersensitivity pneumonitis (especially acute phase) | ||
| • Arthus reaction to vaccination | ||
| Type IV - Delayed hypersensitivity | T-cell mediated | • Tuberculosis / tuberculin skin reaction |
| • Graft versus host disease | ||
| • Allergic contact dermatitis | ||
| • Scabies | ||
| • Extrinsic allergic alveolitis (especially chronic phase) | ||
| • Multiple sclerosis | ||
| • Guillain-Barre syndrome | ||
| Type V | Antibodies that recognise and bind to the cell surface receptors. |
This either stimulating them or blocking ligand binding | • Graves' disease • Myasthenia gravis |