Correlation between cysteinyl leukotriene release from leukocytes and clinical response to a leukotriene inhibitor.

STUDY OBJECTIVES Antileukotriene drugs are widely used in patients with bronchial asthma, but not all patients show significant clinical improvements, and no factors have been identified that are correlated with the clinical response to these drugs. This study was designed to examine the factors correlated with a response to a leukotriene receptor antagonist, pranlukast, in patients with asthma. DESIGN WBC counts, IgE, and ex vivo leukotriene release from leukocytes were measured, and 31 patients with asthma were treated with pranlukast, a leukotriene receptor antagonist, for 4 weeks. MEASUREMENTS Outcome measurements included twice-daily peak expiratory flow rate (PEFR), daytime and nocturnal symptoms, and frequency of beta(2)-agonist use. Subjects with a reduction of > 20% in symptom scores or beta(2)-agonist use, or an improvement of PEFR of > 10% were designated as responders; others were designated as nonresponders. Logistic regression analysis assessed the efficacy of models using various allergic markers correlated with the response to pranlukast. RESULTS There were 16 responders and 15 nonresponders. The release of cysteinyl leukotrienes from the leukocytes of the responders was higher than that of the nonresponders (p < 0.05). There was a significant correlation between the clinical response and the release of cysteinyl leukotrienes, but not demographic features, WBC counts, percentage of eosinophils, or serum IgE levels (p < 0.05). Subjects with a release of cysteinyl leukotrienes of > 3,500 pg/mL were 11.0 times more likely to respond to pranlukast than those with < 3,500 pg/mL (95% confidence interval, 2.0 to 60.5). CONCLUSION Cysteinyl leukotriene release from leukocytes is correlated with leukotriene receptor antagonist response.