Hypersensitivity reaction

Hypersensitivity reaction - Type II

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What is Hypersensitivity reaction - Type II?

Hypersensitivity means that the body responds to a particular substance (called allergens) in an exaggerated fashion, where it does not happen in normal circumstances. There are 4 types of hypersensitivity reaction, type I, II, III and IV. They are different in terms of the disease manifestation and pathological processes. However, only type II hypersensitivity reaction will be discussed here.

Type II hypersensitivity reaction is also called antibody mediated hypersensitivity reaction because this is the differentiating feature from other types of hypersensitivity.

Type II hypersensitivity reaction can occur in many parts of the body. Generally, they include:

lungs

skin

blood system

nerve

thyroid

Who gets Hypersensitivity reaction - Type II?

The cases of different diseases vary widely. However, certain diseases such as Grave's disease can be common. Also, diseases such as systemic lupus erythematosus can have cases of 1.8-7.6 per 100,000.

Note that systemic lupus erythematosus is a disease of mixed hypersensitivity - type II and III hypersensitivity reaction occur in this disease.

Predisposing Factors

Depending on the manifestations of different type II hypersensitivity diseases, there are different risk factors as well.

There are some gender differences between diseases of type II hypersensitivity. Some diseases are more common in women such as systemic lupus erythromatosus (SLE) and Grave's disease. However, diseases such as Goodpasture's syndrome are more common in men.

Also, ethnic differences do occur in the diseases of type II hypersensitivity diseases.

Progression

Type II hypersensitivity reaction is characterised by antibodies directed toward antigens (substance that attracts the antibody to bind with) that are present on cell surfaces outside the cells.

The antigens can either be from the body itself or from outside the body (for example, bacteria or microorganisms that infect the body).

By the various biochemical mechanisms, the end result are tissue damage to the body.

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