Leukotrienes (LTs) are lipid mediators prominently exerting proinflammatory responses. They are divided in two classes: cysteinyl LTs (cysLTs) which have a thioester linkage and LTB₄¹. LTB₄, a chemoattractant, plays a prominent role in the recruitment and activation of leukocytes².

LTB₄ acts through two receptors which belong to the G-protein coupled receptor superfamily: BLT1 and BLT2. BLT1 displays high affinity for LTB₄ and is highly expressed in leukocytes including granulocytes, macrophages, mast cells, dendritic cells and effector T cells³ and is expressed to much lower levels in the spleen, thymus, heart, skeletal muscle, brain and liver^2-4. BLT2 on the other hand is a low affinity receptor which does not display selectivity towards LTB₄⁵. Its expression is much more ubiquitous than that of BLT1. It is expressed in most human tissues, with the highest expression being in the spleen, liver, ovary, and leukocytes^2,5-8. The two receptors could couple and activate different G-proteins, depending on the cell type and the cellular events activating the receptors². However, activation of BLT1 usually correlates with increasing intracellular concentrations of Ca²⁺.

The LTB₄/BLT1 system is involved in many allergic reactions as well as asthma induced as an allergic response, where it plays a significant role in recruiting neutrophils and effector T cells into lungs as part of an inflammatory response induced by allergens¹.