Type 1 Hypersensitivities occur when an IgE antibody reacts with an allergen and triggers mast  cell degranulation. Allergens can range from harmless substances such as pollen to hazardous substances such as insect venom or even food intolerances. 

Type 1 Hypersensitivity

Type II Hypersensitivities are also known as cytotoxic hypersensitivities. Cytotoxic hypersensitivity occurs when a IgM and IgG antibodies interact with cellular antigens. These interactions may activate the Complement System or antibody-dependent cell-mediated cytotoxicity with cytotoxic T cells.

Type II (Cytotoxic) Hypersensitivities

Type III Hypersensitivities involve the interactiosn of IgM, IgG, and sometimes IgA antibodies with antigen to form immune complexes. The accumulation of these immune complexes within tissue can lead to tissue damage.

Type III Hypersensitivity

Type IV hypersensitivities occur when activated macrophages or cytotoxic T cells  lead to tissue damage. 

Type IV Hypersensitivity

The four types of hypersensitivity reactions are classified by their specific immune mechanism:
- Type I
- Type II
- Type III
- Type IV

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Hypersensitivity is an exaggerated response that sometimes occurs when an antibody interacts with an antigen.

Hypersensitivity

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Types of Hypersensitivity

Inflammation of the lungs due to inhalation of an allergen. Hypersensitivity Pneumonitis can be due to both type III or type IV hypersensitivities.

Hypersensitivity Pneumonitis

There are several treatment options for hypersensitivities including:
- Desensitization
- Emergency systemic anaphylaxis
- Anti-inflammatory drugs

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