What are hypersensitivity disorders?

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.Click to see full answer. Herein, what are the 4 types of hypersensitivity reactions? 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) Likewise, 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. In this regard, what are hypersensitivity diseases? Hypersensitivity diseases reflect normal immune mechanisms directed against innocuous antigens. They can be mediated by IgG antibodies bound to modified cell surfaces, or by complexes of antibodies bound to poorly catabolized antigens, as occurs in serum sickness.What are the signs and symptoms of hypersensitivity?Signs and symptoms of acute, subacute, and chronic hypersensitivity pneumonitis may include flu-like illness including fever, chills, muscle or joint pain, or headaches; rales; cough; chronic bronchitis; shortness of breath; anorexia or weight loss; fatigue; fibrosis of the lungs; and clubbing of fingers or toes.