The Role of Bronchial Responsiveness to Leukotrienes in Antigen-Induced Immediate and Late Asthmatic Response

: In order to clarify the role of leukotriene in the antigen-induced asthmatic response, we carried out mite-antigen, leukotriene D4 (LTD4) and histamine inhalation tests in 21 mite-sensitive atopic asthma patients, and investigated the relationship between the bronchial responsiveness to mite (PD20-Mite) and that to LTD4 and histamine (PD20-LTD4, PD20-Hist). We then compared PD20-LTD4 and PD20-Hist between the groups with and without late asthmatic response (LAR), and investigated the relationship between the peak percentage fall of FEV1.0 in LAR (magnitude of LAR) and PD20-LTD4 and PD20-Hist. There were significant correlations between PD20-LTD4 and PD20-Mite (r = 0.590, p < 0.01), and between PD20-Hist and PD20-Mite (r = 0.669, p < 0.001). The bronchial responsiveness to LTD4 and histamine was significantly higher in the group with LAR. In addition, PD20-LTD4 showed a significant negative correlation with the magnitude of LAR (r = 0.724, p < 0.001). Furthermore we analyzed the relationship between PD20-LTD and the ratio of the magnitude of LAR to that of IAR (immediate asthmatic response), because there was a significant correlation between the magnitude of IAR and that of LAR (r = 0.842, p < 0.001) in 16 asthmatic patients with dual asthmatic response, and found that the correlation coefficient was also very high (r = -0.836, p < 0.001). These results suggest an important role of leukotriene in the antigen-induced asthmatic response.