Osmosis video - Type IV hypersensitivity

Type IV hypersensitivity is a type of delayed-type immune response, in which the immune system responds to an antigen several hours or days after exposure. It is also known as cell-mediated hypersensitivity because tissue damage involves T cells. This can be via either CD4+ T helper cells, which help coordinate the attack, or CD8+ killer or cytotoxic T cells, which directly destroy host cells. Examples include contact dermatitis, poison ivy, tuberculin skin test, and certain drug reactions, such as allopurinol. Treatment options for Type IV hypersensitivity may include medications like corticosteroids and avoiding exposure to the triggering antigen.