Which type of hypersensitivity involves antibodies against cell-surface or matrix antigens leading to cytotoxic injury?

Which type of hypersensitivity involves antibodies against cell-surface or matrix antigens leading to cytotoxic injury?

• A. Type I hypersensitivity
• B. Type II hypersensitivity
• C. Type III hypersensitivity
• D. Type IV hypersensitivity

Answer: (B)

Antibody-mediated cytotoxic hypersensitivity. Here, antibodies (usually IgG or IgM) bind to antigens on the surface of cells or on extracellular matrix components. This binding flags the target for destruction by the immune system, either by activating complement and causing cell lysis, by promoting phagocytosis through Fc receptors, or by recruiting NK cells for antibody-dependent cellular cytotoxicity. The result is cytotoxic injury to the target cell or tissue. Classic examples include autoimmune hemolytic anemia, Goodpasture syndrome, and autoimmune thrombocytopenia. This differs from the other types: Type I is driven by IgE and immediate mast cell degranulation; Type III involves immune complex deposition; Type IV is T-cell–mediated delayed-type hypersensitivity.

Antibody-mediated cytotoxic hypersensitivity. Here, antibodies (usually IgG or IgM) bind to antigens on the surface of cells or on extracellular matrix components. This binding flags the target for destruction by the immune system, either by activating complement and causing cell lysis, by promoting phagocytosis through Fc receptors, or by recruiting NK cells for antibody-dependent cellular cytotoxicity. The result is cytotoxic injury to the target cell or tissue. Classic examples include autoimmune hemolytic anemia, Goodpasture syndrome, and autoimmune thrombocytopenia. This differs from the other types: Type I is driven by IgE and immediate mast cell degranulation; Type III involves immune complex deposition; Type IV is T-cell–mediated delayed-type hypersensitivity.