Journal of Allergy & Therapy

Hypersensitivity and its Related Reactions

Julie C. Brown^* Department of Allergy Emergency Medicine, University of Washington, Seattle, Washington, United States
^*Correspondence: Julie C. Brown, Department of Allergy Emergency Medicine, University of Washington, Seattle, Washington, United States, Email:

Received: 08-Jul-2021 Published: 28-Jul-2021, DOI: 10.35248/2155-6121.21.12.e258

Editorial Note

When a person who has been sensitised to an allergen is exposed to it, their immune system is able to mount a rapid immunological response. An allergic reaction like this is known as hypersensitivity and is classified as a type I allergy. Allergens can also include items that are naturally more dangerous, such as animal dander, moulds, or pollen. Allergens can also be chemicals that are naturally more hazardous, such as insect venom or pharmaceutical medications. People who have become sensitised to substances such as peanuts or shellfish may develop allergic reactions as a result of their food intolerances. Regardless of the allergen, the initial exposure triggers a type 1 IgE antibody response, which makes a person susceptible to a type I allergic reaction reaction following repeated exposure. Type I hypersensitivity reactions can be regional or systemic in nature. Pollinosis rhinitis, hives, and allergies are examples of localised type I hypersensitivity reactions. Anaphylaxis or anaphylaxis is a term used to describe systemic type I hypersensitivity reactions. Although anaphylaxis shares many symptoms with localised type I hypersensitivity reactions, In reality, death can happen minutes after the first signs and symptoms appear. Late-section reactions in type I hypersensitivities can occur 4–12 hours after the main section and are mediated by eosinophils, neutrophils, and lymphocytes, which are attracted to mast cells by chemotactic signals. The activation of these recruited cells causes the release of additional chemical mediators, which cause tissue damage and late-phase symptoms like as skin swelling and redness, coughing, wheezing, and nasal discharge. Individuals with genes for maladaptive traits, such as severe type I hypersensitivity reactions to generally harmless environmental components, are likely to have lower reproductive success. With this form of evolutionary selective pressure, such developments would not be expected to continue a population. This shows that hypersensitivities of type 1 may serve an adaptive purpose. There's evidence that the IgE produced during type 1 hypersensitivities is actually meant to fight helminth infections2. Helminths are one of the few organisms that produce IgEfocused proteins. There may be evidence that helminth infections at a young age lessen the risk of type I hypersensitivities to seemingly harmless drugs later in life. As a result, allergies are likely to be an unpleasant side effect of strong selection in the mammalian lineage, or a forerunner to a defence against parasitic worms.

Type II (Cytotoxic) Hypersensitivities Immune reactions classified as kind II hypersensitivities, or cytotoxic hypersensitivities, are caused by IgG and IgM antibodies binding to cell surface antigens or matrix-associated antigens on basement membranes. These antibodies can either activate complement, causing an inflammatory reaction and cell lysis in the target cells, or they can be involved in Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), where cytotoxic T lymphocytes attack the target cells. In certain situations, the antigen may be a self-antigen, in which case the reaction could be classified as an autoimmune illness. (See Autoimmune Disorders for a list of autoimmune diseases.) Antibodies may also attach to exogenous cell-surface chemicals, such as antigens related with diagnosis found on Red Blood Cells(RBCs), in other circumstances. This results in antibody-mediated coating of RBCs, complement activation, and complement-mediated lysis of RBCs, as well as opsonization of RBCs for phagocytosis. Hemolytic Reaction (HTR) and Hemolytic Disease of the New Child (HDN) are two examples of type II hypersensitivity reaction reactions involving RBCs. Four summarises type II hypersensitivity, which can be discussed in greater depth. Immunohematology is the research of blood and blood-forming tissue in relation to immune responses. Antibody-induced hypersensitivities to blood cells are classified as type II hypersensitivities, and so belong to the field of immunohematology.