Enhanced extracellular growth of Staphylococcus aureus in the presence of selected linear peptide fragments of human interleukin (IL)-1 beta and IL-1receptor antagonist

Replication of Staphylococcus aureus is significantly enhanced in the prese nce of recombinant interleukin (IL)-1 beta. In this study, specific binding of IL-1 beta to the surface of S. aureus significantly increased growth of S. aureus in the presence of IL-1 beta and IL-1ra in a concentration-depen dent manner. Although IL-1ra enhanced the growth of S. aureus, there was a significant reduction in IL-1 beta -mediated growth enhancement of S. aureu s when 25-fold excess amounts of IL-1ra (in comparison with the IL-1 beta c oncentration) were present in the culture medium. Thus, IL-1 beta may influ ence the growth of S. aureus through a receptor-mediated event. By using 5 linear peptides spanning limited regions of IL-1 beta, the growth-promoting regions were localized to amino acid residues 118-147 and 208-240. These r esults build on the newly evolved concept of direct interactions between th e soluble mediators of inflammation and infectious agents.