Annals of allergy
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Anaphylactic reactions usually occur seconds to minutes after exposure to the relevant antigen. Late onset, biphasic, and protracted anaphylaxis also occur. The incidence of prolonged responses is unknown, but may be common. In all nonfood-related cases, levels of tryptase were not measured during protracted episodes. Tryptase has been shown to be a useful specific indicator of mast cell involvement in anaphylaxis. ⋯ The elevated serum tryptase levels at 96 and 120 hours following the onset of symptoms strongly suggest that continued mast cell degranulation can occur during protracted anaphylaxis. This strengthens the argument that mast cell activation is important in the pathophysiology of protracted anaphylaxis.