Pathophysiology : The Biologic Basis for Disease in Adults and Children: Chapter 9: Alterations in Immunity and Inflammation

3 variables which interact for hypersensitivity to cause disease development - 1. an alteration/insult in immunologic homeostasis 2. an individual's genetic makeup, which determine the degree of the resultant immune response to the insult 3. an immunologic process that causes symptoms of disease 4 mechanisms of hypersensitivity reactions - -type I: immunoglobulin E (IgE) -mediated -type II: tissue-specific -type III: immune-complex-mediated type IV: cell-mediated allergy - -deleterious effects of hypersensitivity to environmental changes -hypersensitivity response against environmental antigen, most are Type I alloimmunity - -immune system of one individual produces an immunologic reaction against tissues of another individual -ex: transient neonatal diseases, transplant rejection and transfusion reactions Arthus reaction - -prototypic example of localized immune complex-mediated inflammatory response, caused by repeated local exposure to an antigen that binds with preformed antibody and forms immune complexes in the walls of local vessels -symptoms within 1 hour of exposure and peak at 6-12 hours atopic - individuals with genetic predisposition toward particular allergy atopic dermatitis - widely distributed lesions, immediate hypersensitivity autoimmunity - -a disturbance in the immunological tolerance of self-antigens -body's immune system begins to recognize self antigens as foreign clinical desensitization to allergens - -small quantities of allergen injected at increasing doses, over prolonged period -may reduce severity of reaction, risk of systemic anaphylaxis contact dermatitis - inflammatory rash marked by itching and redness, caused by contact with allergens, delayed hypersensitivity, only at site of contact