NR 507 Week 1 Edapt; Hypersensitivity

Hypersensitivity is an exaggerated immunologic response, or overreaction, to a foreign antigen or autoimmunity (i.e., a physiological response against an endogenous "self"-antigen). This overreaction is a form of protection to alert the body to an actual or potential health problem. Hypersensitivity reactions are not due to antigens directly but from the inflammatory processes generated by antibodies, immune complexes, or cell-mediated responses. Immediate hypersensitivity is mediated by IgE antibodies, which result in an allergy, anaphylaxis, or atopic disease. The NP should expect the client to have a type 1 hypersensitivity to recent medication use, which can include these immediate reactions as clinical manifestations: urticaria, wheezing, vomiting, and diaphoresis. Hypertension and bradycardia are not associated with immediate hypersensitivity reactions. Characterized by the rapid release of proinflammatory mediators like histamine, leukotrienes, and cytokines in response to allergen exposure, mast cells are the primary effector cells responsible for initiating and mediating type 1 hypersensitivity reactions. Type 3 hypersensitivity reactions involve the formation of immune complexes that can deposit in tissues, leading to complement activation and inflammation. This process can cause tissue damage and is associated with systemic lupus erythematosus (SLE) and serum sickness. Type 1 reactions are mediated by IgE antibodies, and type 2 are mediated by IgG or IgM antibodies. Type 4 reactions are activated by T-helper cells. Anaphylactic Reaction Antigen B-cell Plasma cell IgE Mast cell Histamine Think Acid A: Allergic/Anaphylactic/Atopic (Type 1) C: Cytotoxic (Type 2) I: Immune Complex (Type 3) D: Delayed (Type 4) A type 2 cytotoxic reaction is mediated by IgG or IgM antibodies. Anti-A antibodies in type B blood mix with type A blood Antibodies attach to surface antigen of type A RBC Complement activated, type A RBC cell wall attacked Lysis of type A RBC Phagocytosis A type 3 reaction is mediated by immune complexes. Immune complex Antibodies bind to antigens Immune complexes form Complexes deposit in blood vessels or tissues Activation of complement Inflammatory response at site of deposit Release of lysosomal enzymes and chemical mediators Tissue damage A type 4 delayed reaction is mediated by cellular response. Macrophage presents antigen Sensitization of T lymphocyte Release of lymphokines Inflammation and lysis of antigen-bearing cells in the tissue Tissue destruction Patho of Type 1 reactions Type 1 hypersensitivity reactions, also known as immediate hypersensitivity reactions, are characterized by the rapid release of proinflammatory mediators like histamine, leukotrienes, prostaglandins, and cytokines in response to allergen exposure. These local or systemic effects are mediated by IgE antibodies, which result in an allergic reaction, anaphylaxis, or atopic disease. Physiological manifestations include the following: vasodilation bronchial smooth muscle contraction mucus production The most common allergic reactions are type 1 reactions to environmental antigens (e.g., pollen, insects [bee venom], tree nuts, and medications). Allergic reactions can also occur to foods, latex, animal hair, and pet dander. Type 1: Allergic rhinitis Allergic rhinitis, often referred to as hay fever, is a common type 1 hypersensitivity reaction and involves immunoglobulin E (IgE) mediated release of antibodies to the antigen. This results in mast