press-5.qxd 11/28/07 3:01 PM Page 399 ORIGINAL ARTICLE Arch. Immunol. Ther. Exp., 2007, 55, 399–403 PL ISSN 0004-069X DOI 10.1007/s00005-007-0045-3 Immunomodulation by α(1)-proteinase inhibitor: lack of chemotactic effects of recombinant human α(1)-proteinase inhibitor from yeast on human peripheral blood granulocytes Birgit Mosheimer, Reinhard Alzner and Christian J. Wiedermann Division of General Internal Medicine, Department of Medicine, Medical University of Innsbruck, A-6020 Innsbruck, Austria Received: 2007.07.24, Accepted: 2007.10.02, Published online first: 2007.12.03 Abstract Introduction: Recombinant α(1)-proteinase inhibitor, clinically developed for inhalative augmentation therapy in patients with α(1)-proteinase inhibitor deficiency or cystic fibrosis, may directly contribute to leukocyte accumulation as it may func- tion as a chemoattractant. The migratory effects of yeast-derived human recombinant α(1)-proteinase inhibitor on human peripheral blood neutrophils and eosinophils were therefore tested in vitro. Materials and Methods: Human peripheral blood leukocytes were prepared from forearm venous blood and tested for migra- tion toward various preparations of yeast-derived recombinant α(1)-proteinase inhibitor in modified Boyden-chamber micropore filter assays. Results: No direct effects of yeast-derived recombinant human α(1)-proteinase inhibitor on in vitro migration of isolated neu- trophils or eosinophils were seen. Conclusions: The lack of direct chemotactic effects of recombinant human α(1)-proteinase inhibitor despite anti-inflamma- tory effects in other biological activities of leukocytes may contribute to the preserved antibacterial defense mechanisms observed in patients under experimental augmentation therapy with inhaled α(1)-proteinase inhibitor. Key words: neutrophils, eosinophils, chemotaxis, antiproteinase, emphysema. Corresponding author: Prof. Dr. Christian J. Wiedermann, Department of Medicine, Central Hospital of Bolzano, L. Böhler Street 5, 39100 Bolzano (BZ), Italy, tel.: +39 471 908190, fax: +39 512 471 908303, e-mail: Christian.Wiedermann@asbz.it INTRODUCTION In the healthy human lung, α(1)-proteinase inhibitor (A1PI) is present at high concentrations and acts as an anti-protease screen to prevent the deleterious effects of free elastase [2]. People with a deficiency of A1PI are at risk for emphysema as a result of low levels of A1PI in the lungs in the presence of neutrophil elastase [25]. In cystic fibrosis airways, A1PI is complexed [3] and proteolytical- ly inactivated [26], resulting in an imbalance of proteases and anti-proteases. The discovery of the structure and function of the A1PI protein and its subsequent isolation and purification have allowed replacement therapy (so- called “augmentation therapy”) aimed at preventing the progression of the lung disease associated with deficiency or cystic fibrosis [9]. Isolation of the gene and advances in gene therapy further broadened the potential for specific therapy by the synthesis of recombinant A1PI. Therapeutic concentrates are prepared from the blood plasma of blood donors and are the only form of A1PI available for therapy so far. All commercially available A1PI products differ from the A1PI directly analyzed in plasma (summarized in Table 1). The observed differences between the products most likely do not play a substantial biologic role because all three products have similar half-lives in humans and neutral- ize neutrophil elastase to the same extent [12]. To attenuate the deleterious effects of free elastase on pulmonary structure and host defense mechanisms more effectively, the inhalation of A1PI has been pro- posed as a therapeutic strategy in both A1PI deficiency and cystic fibrosis patients. Inhalation of human plasmat- ic A1PI increased A1PI levels in adult patients with cystic fibrosis and decreased the levels of elastase activity, neu- trophils, pro-inflammatory cytokines, and the numbers of Pseudomonas aeruginosa [7]. Trends of reduced elastase