Distinct antithrombin III preparations deactivate IL-8-induced neutrophil chemotaxis with different potency

Background

Neutrophil activation is a crucial step in the pathogenesis of sepsis and subsequent development of multiple organ failure. Antithrombin III (ATIII) exerts direct effects on neutrophils by inhibiting chemokine-induced migration. The positive outcome of animals in models of severe sepsis treated with ATIII may be due to this neutrophil-dependent action. The aim of the present study was to determine the potency of different ATIII preparations in inhibiting neutrophil chemotaxis compared to monoclonal antibody-purified ATIII.

Methods

Human neutrophils were isolated using standard preparation methods. Cell migration was tested in modified Boyden microchemotaxis chambers bearing nitrocellulose filters in the leading front assay. Human neutrophils were incubated with seven different ATIII preparations at various concentrations (1 μIU/ml to 5 IU/ml) for 20 min. Immuno-purified ATIII served as positive control. After washing twice, neutrophils migrated toward interleukin-8 (1 nM) for 30 min in humidified atmosphere at 37°C. After staining of the cells, migration depth was measured microscopically.

Results

At concentrations below 10 mIU, neutrophil chemotaxis toward interleukin-8 was decreased by the ATIII preparations with different potencies, whereas at higher concentrations (1 IU and 5 IU) no significant differences could be observed. Deactivation of neutrophil chemotaxis was most pronounced by Kybernin^®P (Aventis Behring, Marburg, Germany) at 100 μIU and was comparable in potency to homologous deactivation with IL-8. The purified ATIII inhibited interleukin-8-induced chemotaxis at all concentrations tested (1 μIU to 5 IU).

Conclusion

We suggest that antiinflammatory activity of ATIII may be due to deactivation of chemokine-induced leukocyte migration. Commercially available ATIII-preparations at distinct concentrations show significant differences in their ability to deactivate neutrophil chemotaxis toward interleukin-8. This may suggest also different activities in vivo depending on the various preparation procedures.