What are the 4 types of hypersensitivity reactions?

What are the 4 types of hypersensitivity reactions?

The four types of hypersensitivity are:

• Type I: reaction mediated by IgE antibodies.
• Type II: cytotoxic reaction mediated by IgG or IgM antibodies.
• Type III: reaction mediated by immune complexes.
• Type IV: delayed reaction mediated by cellular response.

How does Type 1 hypersensitivity occur?

Type I hypersensitivity (or immediate hypersensitivity) is an allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen. Type I is distinct from type II, type III and type IV hypersensitivities. Exposure may be by ingestion, inhalation, injection, or direct contact.

What is a type III hypersensitivity reaction?

In type III hypersensitivity reaction, an abnormal immune response is mediated by the formation of antigen-antibody aggregates called “immune complexes.” They can precipitate in various tissues such as skin, joints, vessels, or glomeruli, and trigger the classical complement pathway.

What is the difference between Type 2 and 3 hypersensitivity?

Type 2 hypersensitivity reactions may occur in response to host cells (i.e. autoimmune) or to non-self cells, as occurs in blood transfusion reactions. Type 2 is distinguished from Type 3 by the location of the antigens – in Type 2, the antigens are cell bound, whereas in Type 3 the antigens are soluble.

What are the 5 types of hypersensitivity?

Hypersensitivity

• Type I: IgE mediated immediate reaction.
• Type II: Antibody-mediated cytotoxic reaction (IgG or IgM antibodies)
• Type III: Immune complex-mediated reaction.
• Type IV: Cell-mediated, delayed hypersensitivity reaction.

What are the 5 types of allergic reactions?

What are the four types of allergic reactions?

• bronchial asthma,
• allergic rhinitis,
• allergic dermatitis,
• food allergies,
• allergic conjunctivitis (eye inflammation) and.
• anaphylaxis (allergic shock).

What is a Type II hypersensitivity reaction?

Type II hypersensitivity reaction refers to an antibody-mediated immune reaction in which antibodies (IgG or IgM) are directed against cellular or extracellular matrix antigens with the resultant cellular destruction, functional loss, or damage to tissues.

What is an example of type 3 hypersensitivity?

Examples of type III hypersensitivity reactions include drug-induced serum sickness, farmer’s lung and systemic lupus erythematosus.

What is an example of type 4 hypersensitivity?

Ocular examples of type IV hypersensitivity include phlyctenular keratoconjunctivitis, corneal allograft rejection, contact dermatitis, and drug allergies, although drug sensitivities can lead to all four types of hypersensitivity reaction.

What is a Type 1 hypersensitivity reaction?

Type I hypersensitivity is also known as an immediate reaction and involves immunoglobulin E (IgE) mediated release of antibodies against the soluble antigen. This results in mast cell degranulation and release of histamine and other inflammatory mediators.

What are examples of hypersensitivity reactions?

Type I hypersensitivity reactions can be seen in bronchial asthma, allergic rhinitis, allergic dermatitis, food allergy, allergic conjunctivitis, and anaphylactic shock. Anaphylaxis is a medical emergency as it can lead to acute, life-threatening respiratory failure. It is an IgE-mediated process.

What is an example of type 2 hypersensitivity?

Examples of type II HS include some forms of anemia, blood transfusion reactions, certain platelet disorders, and some types of tissue transplant rejection.