Mast cells late phase inflammatory reaction

Type I hypersensitivity reactions usually occur within minutes to hours of exposure to an antigen in sensitized individuals. The immediate allergic response is initiated 5 to 30 minutes after allergen exposure and resolves in 30 to 60 minutes.This may be followed by the late-phase reaction, which is more severe and of greater duration. The late phase develops 4 to 6 hours after the initial response and may last up to 2 days. Neutrophils, eosinophils, macrophages, lymphocytes, basophils, and mast cells are involved in the late-phase inflammatory reaction, resulting in tissue damage. 

Do Mast Cells Initiate Late Phase Inflammatory Reactions ... 

From 4 to 8 hours after the initial exposure to an allergen, a late-phase reaction may occur, which is thought to be due to cytokines released primarily by mast cells and thymus-derived helper lymphocytes. This inflammatory response likely is responsible for persistent, chronic symptoms including nasal congestion. 

Type IVb. Corresponds to the Th2-type immune response. Th2 T cells secrete the cytokines EL-4, EL-13, and EL-5, which promote B cell production of IgE and IgG4, macrophage deactivation as well as mast cell and eosinophil responses. The high production of EL-5 leads to an eosinophilic inflammation, which is the characteristic inflammatory cell type in many drug hypersensitivity reactions (Pichler 2003). In addition, there is a link to type I reactions because Th2 cells boost IgE production by EL-4/EL-13 secretion. Thus, type IVb reactions may actually be involved in the late phase allergic inflammation of the bronchi or nasal mucosa (asthma and rhinitis), which were initiated by IgE on mast cells or basophils. Another in vivo correlate might be infestations with nematodes, eosinophU-rich maculopapular exanthema, or other T cell-dependent diseases with hypereosinophilia. 

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