LTB4R and Arthritis: The sequential and hierarchical role of different chemoattractants during neutrophil-mediated inflammation has been convincingly demonstrated in the K/BxN serum-transfer arthritis model.47,48 Initial production of LTB4, which binds to the BLT1 GPCR on neutrophils, is required for initial recruitment of the first wave of cells into the inflamed joint.