Mouse anti Human elastase antibody, clone 39A recognizes human neutrophil elastase, also known as elastase-2, Bone marrow serine protease, PMN elastase or Medullasin. Elastase is a 238 amino acid ~27 kDa enzyme with an addiional 29 amino acid signal and pro-peptide region. Mutations of the ELA2 gene can lead to a number of hematopoietic disorders including cyclic hematopoiesis (CH) characterized by a 21 day cycle of bone marrow derived blood cell production with neutrophil numbers ranging between normal levels and almost zero (Horwitz et al. 1999) and severe congential autosomal neutropenia (SCN1) demonstating developmental arrest of granulopoiesis at the promyelocyte stage (Bellanné-Chantelot et al. 2004) with both conditions leading to a predisposition to bacterial infections..