Proteinase 3 mRNA expression is induced in monocytes but not in neutrophils of patients with cystic fibrosis

Proteinase 3 (PR3), a serine proteinase which can degrade lung tissue, is p resent in the cystic fibrosis (CF) sputum, In the present study, PR3 protei n and mRNA expression was determined in circulating neutrophils and monocyt es, CF neutrophils contained similar PR3 concentrations as healthy controls and poorly expressed PR3 mRNA. In contrast, CF monocytes showed significan tly higher PR3 concentrations than controls, together with an upregulation of PR3 mRNA expression especially during pulmonary exacerbation. Interestin gly, antibiotic treatment fully abrogated PR3 mRNA expression and decreased PR3 protein in monocytes, Our findings highlight a potential role of monoc yte-derived PR3 in CF-associated airway inflammation. (C) 1999 Federation o f European Biochemical Societies.