Question

Hypersensitivity Types and Functions there types?

Answer 1

Our immune system works continuously to keep us healthy and protect us against bacteria, viruses, and other germs. Sometimes, however, this system becomes too sensitive, causing hypersensitivity reactions that can be harmful or even deadly. These reactions are the result of exposure to some type of foreign antigen either on or in the body.
Hypersensitivity Reactions Key Takeaways
Hypersensitivity reactions are exaggerated immune responses to allergens.There are four types of hypersensitivity reactions. Types I through III are mediated by antibodies, while type IV is mediated by T cell lymphocytes.Type I hypersensitivities involve IgE antibodies that initially sensitize an individual to an allergen and provoke a quick inflammatory response upon subsequent exposure. Allergies and hay fever are both type I.Type II hypersensitivities involve the binding of IgG and IgM antibodies to antigens on cell surfaces. This induces a cascade of events that leads to cell death. Hemolytic transfusion reactions and hemolytic disease of newborns are type II reactions.Type III hypersensitivities result from the formation of antigen-antibody complexes that settle on tissues and organs. In an attempt to remove these complexes, underlying tissue is also damaged. Serum sickness and rheumatoid arthritis are examples of type III reactions.Type IV hypersensitivities are regulated by T cells and are delayed reactions to antigens associated with cells. Tuberculin reactions, chronic asthma, and contact dermatitis are examples of type IV reactions.

Answer 2

It divides the hypersensitivity reactions into the following 4 types: Type I reactions (ie, 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.