The definition of late-phase response (LPR) associated with nasal allergy is not as clear as that associated with asthma. Furthermore, LPR and immediate-phase response often act in concert to produce confounding symptoms due to repeated attacks over a short period of time. We examined the nasal airway resistance (NAR), allergic symptoms, eosinophil cationic protein and histamine concentration in nasal surface tissue 30 min before, and 10 min, 1, 3, 5, 7 and 9 h after a house dust (HD) nasal challenge test was performed twice on 10 patients with HD perennial nasal allergy. Nasal airway resistance readings after the HD nasal challenge test were classified into three types based on changes in NAR: type I (short-lasting, five cases)
type II (prolonged, eight cases)
and type III (biphasic, six cases). Delayed increases in NAR were not observed in type I patients with weak responses to nasal challenge. In type II patients, baseline NAR was elevated and numerous basophilic metachromatic cells (BC) were present in the epithelial layer. In type III patients, baseline NAR was not as elevated as it was in type II patients, but marked responses to challenge were noted. In all three types of changes in NAR, eosinophil leukocyte increased at late phase. Moreover, there was no correlation of change in NAR with an increase in the number of eosinophil leukocyte and BC at the epithelial layer in oil three types, which suggests that further study is required to confirm the exact role of eosinophils and basophilic cells in LPR.