latephase

Latephase is a term used across disciplines to describe the later stage of a biphasic process, occurring after an initial early phase. In medical and biological contexts, late phase often refers to events that follow an initial, rapid response and contribute to sustained effects or secondary symptoms.

In immunology and allergology, the late phase reaction refers to the delayed onset of symptoms after exposure to an allergen, typically emerging several hours after contact and persisting for extended periods. It is driven by the recruitment of inflammatory cells such as eosinophils, neutrophils, and T helper cells, and by the release of cytokines and mediators like interleukins, chemokines, prostaglandins, and leukotrienes.

In patch testing and contact dermatitis, a late-phase reaction can be observed 24 to 72 hours after exposure, sometimes lasting days. The late phase differs from the early phase characterized by immediate mast cell degranulation; it reflects cellular recruitment and tissue remodeling.

In research and pharmacology, distinguishing early and late-phase responses helps to evaluate therapies that target prolonged inflammation or delayed effects. The term latephase is thus used as a descriptive label rather than a fixed, field-wide definition, with specifics varying by discipline and experimental design.

See also early phase, inflammatory response, patch testing.