This study was conducted to examine (1) whether an appropriate sputum can be obtained by inducing with inhalation of hypertonic saline in patients with chronic nonproductive cough and (2) whether eosinophils can be detected in the induced sputum. Appropriate samples were obtained by the induction in 25 of 31 patients with bronchial asthma (BA), 12 of 17 patients with cough-variant asthma (CVA), 17 of 20 patients with bronchodilator-resistant cough associated with atopy (atopic cough, AC), and 23 of 25 healthy subjects. Eosinophils were detected in the successfully induced sputum in 100%, 66.6%, and 88.2% of the patients with BA, CVA, and AC, respectively. Detection of eosinophils in induced sputum may be the initial diagnostic procedure for nonproductive cough of allergic nature.

Although it is well recognized that beta-blockers can induce bronchoconstriction only in patients with asthma, mechanisms of the bronchoconstriction are not well known. We hypothesize that bronchoconstriction induced by beta-blockers may result from inflammatory mediators released by allergic reactions. In this study, we developed a guinea pig model for propranolol-induced bronchoconstriction (PIB) after antigen inhalation and investigated the effect of specific thromboxane (TXA2) receptor antagonists, S-1452 and ONO NT-126, on PIB in passively sensitized and artificially ventilated guinea pigs to determine whether TXA2 is involved in PIB. Propranolol caused bronchoconstriction with 10 mg/ml of propranolol was inhaled 20 min after antigen challenge. On the other hand, propranolol did not produce bronchoconstriction after antigen provocation in nonsensitized guinea pigs or after saline provocation in sensitized animals. Pretreatment of the animals with S-1452 in doses of 0.01 and 0.1 mg/kg and ONO NT-126 in doses of 1.0 and 10 micrograms/kg injected intravenously 15 min after antigen challenge as well as before antigen challenge reduced PIB in a dose-dependent manner. Bronchoconstriction caused by methacholine did not induce PIB. These results suggest that TXA2 has an important role in the pathophysiology of the PIB that develops after the allergic bronchoconstriction.

I In nv vo ol lv ve em me en nt t o of f P PA AF F i in n p po os st ta al ll le er rg gi ic c p pr ro op pr ra an no ol lo ol l--i in nd duWe conclude that platelet-activating factor may contribute to the development of propranolol-induced bronchoconstriction after allergic reaction in our guineapig model.

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Although the agreement between the two methods was considered to be good, higher concentrations of capsaicin solution were required to determine the cough threshold in the dosimeter method, resulting in an unpleasant sensation in the throat.