Isolated early response after nasal allergen challenge is sufficient to induce nasal hyperreactivity.

Ten rhinitic patients allergic to grass pollen were challenged with histamine intranasally 24 hours before and 24 hours after nasal provocation with grass pollen. Up to ten hours after allergen provocation nasal lavage fluid was obtained to characterize early and late phase reactions by measuring the levels of histamine and leukotrienes as indicators of mediator release, and albumin as a marker of increased vasopermeability. Ten minutes after allergen challenge with 10,000 BU grass pollen extract LTC4,D4, and albumin significantly increased from 62 to 576 pg/mL (P = .008) and from 15 to 81 micrograms/mL (P = .008), respectively, without significant changes after placebo challenge a week earlier. Although the patients showed increased responsiveness to histamine after allergen challenge compared with a placebo-challenged control group (P = .02), one patient only demonstrated a late phase nasal allergic reaction characterized by recurrence of clinical symptoms eight to ten hours after allergen challenge and recurrence of mediators in lavage fluid. It is concluded that an isolated early response after allergen challenge is sufficient to induce nasal hyperreactivity. A biochemically or clinically defined late phase allergic reaction does not necessarily accompany allergen-induced hyperreactivity.