Type II Hypersensitivity: Pathogenesis and clinical findings Definition: When antigens bind to the body's cell surfaces, forming an "antigen-surface complex" that triggers a maladaptive antibody-mediated immune reaction. These antigens can either be self-antigens, or foreign antigens that a patient has been previously exposed to. Antigen binds receptor on body cell surface - Example: drug (i.e. heparin) binds the surfaces of body cells (i.e. platelets) -> An "antigen-surface complex" is created on the body cell -> B-Cells with specific pre-formed antibodies against these complexes recognize them as foreign -> B-cells produce autoimmune antibodies (IgG, rarely IgM) against either the antigen, the cell surface receptor, or the entire complex -> Antibody binding recruits macrophages and activates the complement cascade, which destroy these cell surfaces #Type2 #Type2 #HypersensitivityReaction #Allergy #Immunology #pathophysiology
