BLT1 and BLT2:: the leukotriene B4 receptors

Two receptors for leukotriene B-4 (LTB4) have been molecularly identified: BLT1 and BLT2. Both receptors are G protein-coupled seven transmembrane domain receptors, whose genes are located in very close proximity to each other in the human and mouse genomes. The two receptors differ in their affinity and specificity for LTB4: BLT1 is a high-affinity receptor specific for LTB4, whereas BLT2 is a low-affinity receptor that also binds other eicosanoids. The two receptors also differ in their pattern of expression with BLT1 being expressed primarily in leukocytes, whereas BLT2 is expressed more ubiquitously. By mediating the activities of LTB4, these receptors participate both in host immune responses and in the pathogenesis of inflammatory diseases. Reduced disease severity in animal inflammatory models seen with LTB4 receptor antagonists and in mice with targeted deletion of BLT1 have revealed important roles for LTB4 and its receptors in regulating pathologic inflammation. (C) 2003 Elsevier Science Ltd. All rights reserved.