- Type I Hypersensitivity reaction . - treatment relieve the symptoms : a- local cold compresses . b- Antihistamines. c- local & systemic corticosteroids.
Work Step by Step
Type I : Immediate ( Anaphylactic ) Hypersensitivity - these reactions occur when an antigen ( allergen ) reacts with cell (= basophils & mast cells ) fixed antibody ( IgE ) leading to degranulation of these cells lesding to release of chemical mediators( include Histamine, bradykinin, serotonin, prostaglandins, esoinophil chemotactic factor of anaphylaxis , platelete activating factor PAF) - these mediators cause vasodilatation & increased premeability of capillaries as well as contraction of smooth muscles & increased mucous secretion causing the manifestations of the disease. Insect Sting - insect venom ( antigen )- antigen antibody reaction in skin ( type I hypersensitivity )- degranulation of mast cells - release of histamine & other mediators - local vasodilatation & increased capillary prmeability - allergic inflammation ( redness, hotness, pain (throbbing), swelling (edema) , loss of function ). - it may lead to Anaphylaxis which is the systemic form of type I hypersensitivity reactions it manifests by shock due to sudden decrease of blood pressure, respiratory distress due to bronchospasm ,cyanosis edema, urticaria etc. shock may lead to death. Treatment of Insect Sting -designed to counteract the effect of released chemical mediators or to block their actions. - drugs used for treatment : 1- corticosterids. 2- antihistamines. 3- in systemic anaphylaxis : epinephrine is given subcutaneously or intravenous.