Abstract
Leukotrienes have been implicated as important mediator in a bronchial asthma. The purpose of this study is to evaluate the degree of participation of leukotrienes on onset of symptoms of nasal allergy.
We measured leukotriene C4 and D4 (LTC4 and LTD4) in nasal secretion by radioimmunoassay combined with high performance liquid chromatography. This method is superior to the one previously reported in specificity, sensitivity and reproducibility. Subjects consisted of 10 patients (aged 8-34 years, average 19) with house dust nasal allergy. The nasal challenge was performed by applying antigen discs on bilateral inferior turbinates for 10 minutes. During the 10 minutes challenge with antigen, the total amount of nasal secretion was collected by means of suction syringes. LTC4 in nasal secretion before challenge was 0.41±0.22 (average±SE) which increased to 2.43±0.85 after challenge. The difference was statistically significant (P<0.02). LTD4 increased in the range of 0.31±0.09 before challenge to 2.72±0.52 after challenge. The difference was also statistically significant (P<0.001). The leukotriene was applied topically on the inferior turbinate unilaterally using a circular filter paper, 3mm in diameter, dipped in LTC4 or LTD4 liquid solution in subjects with nasal allergy and in normal controls. The amount of nasal secretion obtained during 5 minutes provocation period was measured by thread method, which evaluates the amount of secretion from the length of the thread dyed with fluorescin. Nasal airway resistance in bilateral nasal cavities was measured separately by anterior rhinomanometry before and after the challenge with leukotrienes. Change of mucosal swelling was expressed by percentage change of nasal airway resistance. Before the challenge with leukotriene, nasal challenge was performed using ethyl alcohol diluted with saline as a control, because leukotrienes were dissolved in ethyl alcohol. In subjects with nasal allergy, challenge with LTC4 and LTD4 (0.04μg or 0.4μg) on unilateral nasal mucosa induced ipsilateral watery secretion which was significantly larger in amount compared with that induced by ethyl alcohol (P<0.01-0.05). Challenge with LTD4 (0.4μg) on unilateral nasal cavity in the subjects with nasal allergy caused significant swelling of the nasal mucosa in the ipsilateral nasal cavity (P<0.05). As for the amount of nasal secretion and degree of mucosal swelling in the contralateral nasal cavity, no significant differences were observed between leukotrienes and ethyl alcohol. In normal controls LTC4 and LTD4 induced only minimal amount of nasal secretion and minimal degree of mucosal swelling. And there were no significant differences between leukotrienes and ethyl alcohol in terms of stimulatory effects. The data described above shows that in the nasal mucosa in subjects with nasal allergy, hypersensitivity against leukotrienes are present and that nasal secretion and mucosal swelling induced by leukotrienes are mainly due to their direct effects on the nasal glands and the nasal vasculature. Leukotriens may participate in the onset of hypersensitive nasal symptoms in nasal allergy.
