欧博abgWhat are the different types of hypersensitiv
A hypersensitivity reaction occurs when the body produces an unnecessary and undesirable immune response following exposure to a certain antigen.
Many people refer to hypersensitivity as a form of allergy. Most research suggests that there are four types of hypersensitivity reactions, but some evidence suggests that there may also be a fifth type.
Different classes of antibodies moderate types 1, 2, and 3. Experts consider these types immediate hypersensitivity reactions because they occur within 24 hours of exposure to the antigen.
T cells moderate type 4 reactions, and specialists consider this type a delayed hypersensitivity reaction because it usually occurs 48–72 hours after exposure.
Less is known about type 5, but it may be similar to — or a subset of — type 2.
Diagnosis and treatment vary according to the type of hypersensitivity reaction a person experiences and the symptoms and conditions that result from the reaction. With each situation, it is important to identify and remove the cause of the hypersensitivity reaction to minimize further harm.