The cysteinyl leukotrienes (cys-LTs) LTC4, LTD4, and LTE4 are a class of peptide-conjugated lipids formed from arachidonic acid and released during activation of mast cells (MCs). We now report that human cord-blood-derived MCs (hMCs) express the CysLT1 receptor, which responds not only to inflammation-derived cys-LTs, but also to a pyrimidinergic ligand, UDP. hMCs express both CysLT1

Cysteinyl leukotrienes (cysLTs) mediate vascular leakage and bronchoconstriction through the smooth muscle-associated CysLT type 1 receptor (CysLT1R), one of at least two loosely homologous cysLT-binding G protein-coupled receptors. We previously reported that CysLT1R is expressed by cultured human mast cells (