SERPINA1 and alpha 1-antitrypsin deficiency: Neutrophil elastase binding to macrophages induces the release of LTB4,44 a major neutrophil chemoattractant in AATD,45,46 but this pathway is inhibited by AAT leading to reduced LTB4 release in vitro44 and in vivo.47 This reduces neutrophil recruitment to the airways, limiting the potential proteinase damage.