In order to investigate in detail the mechanism of late asthmatic responses (LAR) which seem to be involved in the development of intractable asthma, we prepared an experimental model of bronchial asthma using guinea pigs and examined neutrophil, eosinophil, and leukotriene (LTs) levels in venous blood and bronchoalveolar lavage fluid (BALF). Our results suggest that leukocytosis, and especially neutrophilia and eosinophilia is found in venous blood more with LAR than in IAR and non-attack states in control animals (P<0.01). Moreover, increased neutrophils were found in BALF in LAR compared with IAR and controls (P<0.01) and marked eosinophil infiltration was observed in the peribronchial tissue in LAR compared with IAR and control (P<0.01). Finally LTC4 levels were high in the venous blood and BALF in IAR, and LTB4 levels were also high in BALF in LAR. The data suggests that the accumulation of neutrtophils and eosinophils in peribronchial areas and release of leukotrienes in BALF play important roles in the etiology of LAR.
Actively sensitized model
Late asthmatic response