TSH-receptor antibodies stimulate the thyroid gland to produce free T4 and T3 without TSH.Initially presents with systemic complaints, followed by renal (hematuria) and pulmonary symptoms (dyspnea, hemoptysis, cough).Antibodies attack antigens in the basement membrane of alveoli (pulmonary hemorrhage) and kidneys (nephritis).Major manifestations: arthritis, carditis, Sydenham chorea, subcutaneous nodules, erythema marginatum.Antibodies against the cell wall of Streptococcus also react with the myocardium.Can have petechiae, purpura, epistaxis to severe hemorrhage.Phagocytes destroy sensitized platelets in the blood.
Transfusion reactions (ABO or blood group incompatibility) Type II hypersensitivity can result from the following conditions: Image by Lecturio.Īntibody-mediated effects (when an antibody binds to the cell surface):Īctivation of the complement system, white blood cells, and Fc receptor-bearing effector cells (mainly NK cells), leading to inflammation and injury Image by Lecturio. Fc-bearing effector cell (natural killer or NK cell) binds the antibody Fc region and releases cytotoxic granules leading to lysis of the target cell.
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