What is hypersensitivity disease?
Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. Hypersensitivity reactions require a pre-sensitized (immune) state of the host.
What is a Type 1 hypersensitivity?
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.
What type of hypersensitivity is hemolytic disease of the newborn?
Rh factor incompatibility between mother and fetus can also cause a type II hypersensitivity hemolytic reaction, referred to as hemolytic disease of the newborn (HDN). If an Rh− woman carries an Rh+ baby to term, the mother’s immune system can be exposed to Rh+ fetal red blood cells.
What is antibody mediated hypersensitivity?
Immunology. Type II hypersensitivity, in the Gell and Coombs classification of allergic reactions, is an antibody mediated process in which IgG and IgM antibodies are directed against antigens on cells (such as circulating red blood cells) or extracellular material (such as basement membrane).
What are the 4 types of hypersensitivity?
- Type I: Immediate Hypersensitivity (Anaphylactic Reaction) These allergic reactions are systemic or localized, as in allergic dermatitis (e.g., hives, wheal and erythema reactions).
- Type II: Cytotoxic Reaction (Antibody-dependent)
- Type III: Immune Complex Reaction.
- Type IV: Cell-Mediated (Delayed Hypersensitivity)
What is an example of hypersensitivity?
Examples include anaphylaxis and allergic rhinoconjunctivitis. Type II reactions (ie, cytotoxic hypersensitivity reactions) involve immunoglobulin G or immunoglobulin M antibodies bound to cell surface antigens, with subsequent complement fixation. An example is contact dermatitis from poison ivy or nickel allergy.
Is urticaria Type 1 hypersensitivity?
Indicators of HypersensitivityType I hypersensitivity could be systemic (anaphylaxis or urticarial) or respiratory (asthma). The systemic reaction involves the release of one or more vasoactive amines from histamine, kinins, and serotonin.
What is Type 4 hypersensitivity?
Type IV hypersensitivity is a cell-mediated immune reaction. In other words, it does not involve the participation of antibodies but is due primarily to the interaction of T cells with antigens. These cells persist for many months or years, so that persons who have become hypersensitive to an antigen tend to remain so.
What causes Type 4 hypersensitivity?
Type IV hypersensitivity is mediated by effector T cells, macrophages and other leukocytes that infiltrate a site of antigen exposure and induce a delayed form of inflammatory tissue damage.
What is type II hypersensitivity?
Type II Hypersensitivity. Type II hypersensitivity is an antibody-dependent process in which specific antibodies bind to antigens, resulting in tissue damage or destruction (see Fig. 2-29B).
What is a Type 2 allergy?
In immune system disorder: Type II hypersensitivity. Allergic reactions of this type, also known as cytotoxic reactions, occur when cells within the body are destroyed by antibodies, with or without activation of the entire complement system.
What is an example of delayed hypersensitivity?
Examples of DTH reactions are contact dermatitis (eg, poison ivy rash), tuberculin skin test reactions, granulomatous inflammation (eg, sarcoidosis, Crohn disease), allograft rejection, graft versus host disease, and autoimmune hypersensitivity reactions.