Abstract
Cysteinyl leukotrienes (CysLTs) are a small family of biological signaling lipids produced by active leukocytes that contribute to diverse inflammatory disease states as a consequence of their engagement with dedicated G protein-coupled receptors. Immunization of mice with a CysLT-modified hapten carrier protein yielded novel monoclonal antibodies that display variable binding affinity to CysLTs. Solution binding assays indicated differing specificities among the antibodies tested, with antibody 10G4 displaying a preference for leukotriene C4 (LTC4). X-ray crystallography of a humanized 10G4 Fab fragment in complex with LTC4 revealed that binding induces a hook-like conformation within the hydrocarbon tail of the lipid arachidonic acid moiety. Specific hydrogen bonding to the LTC4 carboxylate groups further stabilized the complex, while a water molecule mediated a hydrogen bond network that connected the N-terminal arm of l-glutathione to both the arachidonyl carboxylate of LTC4 and the antibody heavy chain. Prophylactic administration of two anti-CysLT antibodies in mice followed by challenge with LTC4 demonstrated their in vivo efficacy against acute inflammation in a vascular permeability model. 10G4 ameliorated the effects of acute dextran sulfate sodium-induced colitis, suggesting that anti-CysLT antibodies could provide a therapeutic benefit in the treatment of inflammatory diseases.