The expression and functional role of CysLT₂ receptors in asthma have not been clarified. In this study, we evaluated CysLT₂ receptors expression, and effects of CysLT₂-and CysLT_1/2-receptor antagonists on antigen-induced bronchoconstriction using isolated lung tissues from both asthma and non-asthma subjects.

CysLT₁ and CysLT₂ receptors expression in asthma and non-asthma lung tissue preparations was examined in immunohistochemistry experiments, and their functional roles in antigen-induced bronchoconstriction were assessed using ONO-6950, a dual CysLT_1/2-receptor antagonist, montelukast, a CysLT₁ receptor antagonist, and BayCysLT₂RA, a CysLT₂ receptor-specific antagonist.

CysLT₁ receptors were expressed on the bronchial smooth muscle and epithelium, and on alveolar leukocytes in 5 in 5 non-asthma subjects and 2 in 2 asthma subjects. On the other hand, although degrees of CysLT₂ receptors expression were variable among the 5 non-asthma subjects, the expression in the asthma lung was detected on bronchial smooth muscle, epithelium and alveolar leukocytes in 2 in 2 asthma subjects. In the non-asthma specimens, antagonism of CysLT₂ receptors did not affect antigen-induced bronchial contractions, even after pretreatment with the CysLT₁-receptor specific antagonist, montelukast. However, in the bronchus isolated from one of the 2 asthma subjects, antagonism of CysLT₂ receptors suppressed contractions, and dual antagonism of CysLT₁ and CysLT₂ receptors resulted in additive inhibitory effect on anaphylactic contractions.

CysLT₂ receptors were expressed in lung specimens isolated from asthma subjects. Activation of CysLT₂ receptors may contribute to antigen-induced bronchoconstriction in certain asthma population.