Dual effects of extracellular adherence protein from Staphylococcus aureus on peripheral blood mononuclear cells

J Infect Dis. 2005 Jul 15;192(2):210-7. doi: 10.1086/430948. Epub 2005 Jun 13.


Extracellular adherence protein (Eap) has been suggested as an important virulence factor of Staphylococcus aureus because it enhances bacterial adherence and internalization into eukaryotic cells, interference with T cells, and neutrophil adherence to endothelial cells. We demonstrate that Eap has dual effects on peripheral blood mononuclear cells, depending on its concentration. At low concentrations (up to 9 microg/mL), Eap induces a proliferative response; at higher concentrations, it causes a significant inhibition of T cell proliferation induced by S. aureus supernatants toxic shock syndrome toxin-1 or phytohemagglutinin. A marked increase in apoptotic (i.e., Annexin V and propidium iodide positive) T and B cells could be demonstrated after exposure to the inhibitory concentration of Eap. Human anti-Eap antibodies prepared from polyspecific immunoglobulin G (IgG) blocked the immunomodulatory effects of Eap. Our results demonstrate novel immunomodulatory activities of Eap and identify potential mechanisms of action of intravenous IgG therapy in the treatment of S. aureus infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / pharmacology
  • Bacterial Proteins / physiology*
  • Bacterial Toxins / toxicity
  • Cell Division
  • Enterotoxins / toxicity
  • Humans
  • Leukocytes, Mononuclear / cytology
  • Leukocytes, Mononuclear / microbiology*
  • Lymphocyte Activation / drug effects
  • Lymphocyte Activation / physiology
  • Phytohemagglutinins / pharmacology
  • RNA-Binding Proteins / pharmacology
  • RNA-Binding Proteins / physiology*
  • Staphylococcus aureus / immunology
  • Staphylococcus aureus / physiology*
  • Superantigens / pharmacology
  • Superantigens / toxicity
  • T-Lymphocytes / immunology
  • T-Lymphocytes / microbiology


  • Bacterial Proteins
  • Bacterial Toxins
  • Eap-N protein, Staphylococcus aureus
  • Enterotoxins
  • Phytohemagglutinins
  • RNA-Binding Proteins
  • Superantigens
  • enterotoxin F, Staphylococcal