Which of the following hypersensitivity reactions is considered cytotoxic in nature?

Type 2 hypersensitivity reactions are characterized by cytotoxic mechanisms where antibodies target specific cells or tissues, leading to cell destruction. In this type of hypersensitivity, immunoglobulin G (IgG) or immunoglobulin M (IgM) antibodies bind to antigens on the surface of target cells. This binding activates the complement system, which facilitates the destruction of the target cells through various mechanisms, including opsonization and cell lysis.

This process can occur in several clinical scenarios, including autoimmune hemolytic anemia, where antibodies target red blood cells, and in conditions like Graves' disease, where antibodies stimulate thyroid cells, leading to various systemic effects. The cytotoxic nature of Type 2 hypersensitivity distinguishes it from other hypersensitivity types, as it directly leads to tissue damage through complement activation and antibody-mediated cellular destruction.