late-phase reaction


Also found in: Acronyms.

de·layed re·ac·tion

a local or generalized response that begins 24-48 hours after exposure to an antigen involving sensitized T cells. See: cell-mediated reaction.

late-phase reaction

Inflammation of any part of the body caused by the release of cytokines; leukotrienes B4, C4, and D4; and prostaglandin D2, occurring approx. 6 hr after the body's initial response to an antigen, during a type I hypersensitivity response. Late-phase reactions play a significant role in prolonging illnesses such as asthma after the initial, immediate histamine-based response has subsided. These are treated with and prevented by the use of corticosteroids, such as prednisone, and other drugs.