Hypersensitivity
Specialty	Emergency medicine, immunology

Hypersensitivity (also called hypersensitivity reaction) refers to undesirable reactions produced by the normal immune system. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. The four-group classification was expounded by P. H. G. Gell and Robin Coombs in 1963.^[1]

Coombs and Gell classification

Type V

This is an additional type that is sometimes (often in Britain) used as a distinction from Type 2.^[5]

Instead of binding to cell surface components, the antibodies recognize and bind to the cell surface receptors, which either prevents the intended ligand binding with the receptor or mimics the effects of the ligand, thus impairing cell signaling.

Some clinical examples:

• Graves' disease
• Myasthenia gravis

The use of Type 5 is rare. These conditions are more frequently classified as Type 2, though sometimes they are specifically segregated into its own subcategory of Type 2.

References

External links

• Hypersensitivity definition, types, causes, and general details
• "Hypersensitivity reactions". GPnotebook.

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