mRNA and Protein Expression Levels of Secretory Leukocyte Protease Inhibitor (SLPI) are Severely Reduced in Patients with Severe Congenital Neutropenia (CN)

Secretory Leukocyte Protease Inhibitor (SLPI) is a cationic serine protease inhibitor with antiprotease, primarily anti-NeutrophilELastase (NE), activities. The molecular interaction and the balance between NE and SLPI is tightly regulated. We identified severe diminished levels of SLPI mRNA in myeloid cells and in plasma of severe congenital neutropeniapatients (CN), as compared to cyclic neutropeniapatients (CyN) and to healthy individuals. We further analysed whether diminished levels of SLPI could cause “maturation arrest“ of myeloid cells seen in CN patients. We inhibited SLPI in the myeloid cell line NB4 a…