Our findings suggested that BLT2 negatively regulates CysLT1 function in lung, by suppressing CysLT1 expression; hence, BLT2 deficiency augments cysLTs-CysLT1-dependent bronchoconstriction and vascular leakage, which in turn results in acute respiratory failure and sudden death in BLT2-KO mice after PLY administration. This evidence concerns the gene LTB4R2 and acute respiratory failure.