To clarify the main humoral triggering factor (histamine and/or leukotriene) of the early stage of asthma attacks, the release of histamine and leukotriene C4 (LTC4) from bronchoalveolar lavage (BAL) cells stimulated with Ca ionophore A23187 was examined in 7 patients with atopic asthma, and the results were compared to those in 7 nonatopic asthma patients. 1. The proportion of BAL
basophilic cells was significantly higher in atopic patients than in nonatopic patients (p<0.05). 2. The content of histamine in BAL fluid was significantly higher in atopic (2.3mcg/mℓ) comparted to that in nonatopic patients (0mcg/mℓ)(p<0.001). The content of LTC4 was high in nonatopic (2.4ng/mℓ) than in atopic patients (0.5ng/
mℓ), however, this was not significant. 3. The release of histamine from BAL cells was 32.6% in atopic and 0% in nonatopic patients, and this was significant (p<0.001). The release of LTC4 from BAL cells was significantly higher in nonatopic (11.3ng/10(6)cell) than in atopic (3.5ng/10(6)cell)(p<0.02). The results demonstrate that histamine play more important role in atopic patients
as a main triggering factor of attacks than LTC4. In contrast, in nonatopic patients, LTC4 is more predominant than histamine during early stage of asthma attacks.