Effect of Staphylococcus aureus serine proteinase on the respiratory burst in phagocytic cells in vitro

The in vitro effects of the Staphylococcus aureus serine proteinase (SASP) on the respiratory burst of human blood mononuclear phagocytes and rat lung macrophages were investigated. The generation of reactive oxygen species (ROS), determined by means of luminol-based chemiluminescence, was stimulated by treatment with SASP in both types of the defense cells. Cell activation depended on the concentration of the enzyme and the response of monocytes was an order of magnitude stronger relative to macrophages. The chemiluminescence emission kinetics were different for both cell types and the maximum signal was achieved in approximately 3 and 17 min, respectively. In experiments involving further cell activation by latex particles, macrophages pretreated with various SASP concentrations reacted with enhanced ROS generation whereas for monocytes, the latex-induced chemiluminescence was weakened by the enzyme. The results concerning the modification of the phagocytic host cell activity by SASP suggest that this enzyme might play an important role in pathomechanisms of staphylococcal infections in vivo.