SERPINA1 and alpha 1-antitrypsin deficiency: Exogenous AAT has also been shown to restore efferocytosis and phagocytosis by macrophages exposed to cigarette smoke, due to a reduction in shedding of CD206 and phosphatidylserine receptors.48 This suggests that the increased proteinase levels in the lungs of AATD patients may strip scavenger receptors from the macrophage surface in a similar manner to that shown in cystic fibrosis, where similar or even higher levels of proteinases are present,49 resulting in a reduced ability to bind bacteria as part of phagocytosis.