What is hypersensitivity and its types?

Hypersensitivity reactions can be classified into four types. Type I: IgE mediated immediate reaction. Type II: Antibody-mediated reaction (IgG or IgM antibodies) Type III: Immune complex-mediated reaction. Type IV: Cytotoxic, cell-mediated, delayed hypersensitivity reaction.

What is a hypersensitivity?

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.

What is an example of hypersensitivity?

Type I reactions (i.e., immediate hypersensitivity reactions) involve immunoglobulin E (IgE)–mediated release of histamine and other mediators from mast cells and basophils. Examples include anaphylaxis and allergic rhinoconjunctivitis.

What is the difference between Type 1 and Type 2 hypersensitivity?

Type I hypersensitivity reactions involve immunoglobulin E (IgE) antibody against soluble antigen, triggering mast cell degranulation. Type II hypersensitivity reactions involve IgG and IgM antibodies directed against cellular antigens, leading to cell damage mediated by other immune system effectors.

What causes hypersensitivity?

Hypersensitivity syndrome is caused by a complex set of interactions between a medication, your own immune system, and viruses in your body, especially herpes viruses.

What are the 4 types of allergic reactions?

Four different types of allergic reactions are immediate, cytotoxic, immune-complex mediated and delayed hypersensitivity reactions. Allergic reactions occur when the body’s immune system has a reaction to a substance it sees as harmful, called an allergen.

What is a Type 3 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 4 hypersensitivity?

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.

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 is a Type 2 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 Arthus type hypersensitivity?

The Arthus reaction is a localized inflammatory response, belonging to a typical local subacute type III hypersensitivity reaction.

What is an example of type 4 hypersensitivity?

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

What causes Type 3 hypersensitivity?

Type III hypersensitivity is caused by circulating immunocomplexes (see Fig. 2-29C) and is typified by serum sickness (a medicine reaction in which multimeric drug-antibody aggregates form in solution). Preformed immunocomplexes deposit in various vascular beds and cause injury at these sites.

What type of hypersensitivity is type 1 diabetes?

Type III Hypersensitivity Reaction to Subcutaneous Insulin Preparations in a Type 1 Diabetic.

Is MS a Type 2 hypersensitivity?

Key features of Type II hypersensitivity that are relevant to discussion of their role in MS are specificity for tissue antigens (therefore autospecificity), recruitment of effector leukocyte responses, and activation of complement.

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.

What is an Arthus reaction?

The Arthus reaction is a rare adverse reaction that usually occurs after vaccination with large and more severe local reactions, belonging to type Ⅲ hypersensitivity reaction.

What type of hypersensitivity is asthma?

It is a type I hypersensitivity reaction, that is an immediate exaggerated or harmful immune reaction. Interestingly, only 7% of allergic people develop asthma,43 which can lead us to believe that they present a unique phenotype that distinguishes them from other allergic, but nonasthmatic, individuals.