Comparative aspects of murine proteinase 3

The neutrophilic granule protein proteinase 3 (PR3) is the preferred target antigen of anti-neutrophil cytoplasmic antibodies (ANCA) found in the serum of patients with Wegener's granulomatosis, a systemic small-vessel vasculitis. Due to the lack of data concerning the murine homologue of human PR3, we assessed the neutrophil marker polypeptide PR3 in mice by generating a murine-specific PR3 antibody. In contrast to humans, peripheral blood leukocytes are not the main resource of murine PR3. Interestingly, we could show that the mouse bone marrow is the main PR3 source, indicating that it is a large reservoir for functional neutrophils. This pool of neutrophils could be rapidly mobilized after injection of IL-8. The development of the new PR3 antibody provides a new tool for studying the maturation processes of the murine hematopoietic system and will also support the generation of infectious disease or vasculitis mouse models.