Effect of allergen provocation on inflammatory cell profile and endothelin-like immunoreactivity in guinea-pig airways

The effect of allergen challenge on the number of leucocytes and the concentration of endothelin 1-like immunoreactivity (ET-LI) in bronchoalveolar lavage fluid (BALE) was investigated in guinea-pigs sensitized to Ascaris suum. The animals were twice exposed to allergen aerosol. All animals responded to the second challenge with bronchoconstriction. Twelve hours later, a significant increase in the number of eosinophilic granulocytes in BALE, compared to unsensitized and unprovoked control animals, was noted. Twenty-four hours after provocation, there was also an elevation of ET-LI concentration and content of neutrophils. During the first day post-challenge, the ET-LI values were moderately correlated to the eosinophil levels. One week after challenge, the ET-LI level and the neutrophil count did not differ from corresponding values in control animals whereas the number of eosinophils remained elevated. Pretreatment with dexamethasone before the second allergen challenge did not consistently affect the parameters studied during the first 24 h. Bronchoconstriction induced by carbachol aerosol affected significantly neither the ET-LI concentration nor the number of inflammatory cells in BALE. It is concluded that the allergen-induced inflammation in the guinea-pig airways causes an elevation in the ET-LI concentration in BALE and that this is moderately correlated to the influx of eosinophils during the first 24 h.