Which of the following type of hypersensitivity reactions is found in blood transfusion reaction
Ref Robbins 9/e p205 Antibody-Mediated Diseases (Type II Hypersensitivity) Antibody-mediated (type II) hypersensitivity disorders are caused by antibodies directed against target antigens on the surface of cells or other tissue components. The antigens may be normal molecules intrinsic to cell membranes or in the extracellular matrix, or they may be adsorbed exoge- nous antigens (e.g., a drug metabolite). Antibody-mediated abnormalities are the underlying cause of many human diseases; examples of these are listed in Table 4-3. In all of these disorders, the tissue damage or functional abnormali- ties result from a limited number of mechanisms. Mechanisms of Antibody-Mediated Diseases Antibodies cause disease by targeting cells for phagocyto- sis, by activating the complement system, and by interfer- ing with normal cellular functions (Fig. 4-10). The antibodies that are responsible typically are high-affinity antibodies capable of activating complement and binding to the Fc receptors of phagocytes. * Opsonization and phagocytosis. When circulating cells, such as erythrocytes or platelets, are coated (opsonized) with autoantibodies, with or without complement pro- teins, the cells become targets for phagocytosis by neutrophils and macrophages (Fig. 4-10, A). These phagocytes express receptors for the Fc tails of IgG anti- bodies and for breakdown products of the C3 comple- ment protein, and use these receptors to bind and ingest opsonized paicles. Opsonized cells are usually elimi- nated in the spleen, and this is why splenectomy is of Figure 4-10 Mechanisms of antibody-mediated injury. A, Opsonization of cells by antibodies and complement components, and ingestion of opso- nized cells by phagocytes. B, Inflammation induced by antibody binding to Fc receptors of leukocytes and by complement breakdown products. C, Antireceptor antibodies disturb the normal function of receptors. In these examples, antibodies against the thyroid-stimulating hormone (TSH) receptor activate thyroid cells in Graves disease, and acetylcholine (ACh) receptor antibodies impair neuromuscular transmission in myasthenia gravis.
Anaphylactic type
Cytotoxic type
Type 3 hypersensitivity
Cell mediated hypersensitivity
General anatomy