title: Expression of cell surface markers on methicillin resistant Staphylococcus aureus stimulated lymphocytes.
abstract: OBJECTIVE
  Methicillin-resistant Staphylococcus aureus (MRSA) has gradually been increasing, new strategies in the treatment of MRSA infections are required. This depends on the understanding of the infection pathogenesis and the immune response. This study was therefore designed to determine the immune response which develops during MRSA infection and the role of chemokines in this response, and also to compare the results with the changes occurring after MSSA infection.
  
  
  METHODS
  The expression of the surface markers of human lymphocytes stimulated by heat-killed MRSA or MSSA was analysed by flow cytometry. The chemokine levels in the lymphocytes culture supernatants stimulated or not stimulated by microorganisms were determined by ELISA.
  
  
  RESULTS
  Human peripheral blood mononuclear cells (PBMCs) stimulated by MRSA the levels of CD4(+)CD25(+) regulatory T cells, CD69 expressions in the activated T lymphocytes, CD3(-)CD16(+)CD56(+) NK cells and the levels of MIP-1alpha, MIP-1beta, MCP-1 chemokines increased as compared to the cells not stimulated by MRSA. Although stimulation by MSSA caused an increase in CD25 expression after 24 h, the increase was found to be lower than the one caused by MRSA stimulation. The increase in CD69 expression was statistically significant compared to the cells stimulated by MRSA. Different from the cells stimulated by MRSA, no change was observed in the expressions of CD54 and CD3(-)CD16(+)CD56(+) NK cells in the cells stimulated by MSSA.
  
  
  CONCLUSIONS
  Our findings showed that cellular as well as humoral immunity are critical in MRSA infection and that T cell activation and the increase in chemokines may play a role in the regulation of immune response.
authors.affiliation: Gazi University, Faculty of Medicine, Department of Medical Microbiology, Ankara, Turkey. isilfidan@yahoo.com
authors.forename: Isil
authors.initials: I
authors.lastname: Fidan
authors.forename: Emine
authors.initials: E
authors.lastname: Yesilyurt
authors.forename: Berna
authors.initials: B
authors.lastname: Erdal
authors.forename: Sultan
authors.initials: S
authors.lastname: Yolbakan
authors.forename: Turgut
authors.initials: T
authors.lastname: Imir
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D055612:Cytokine-Induced Killer Cells; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000276:immunology*; D008875:Middle Aged; D013203:Staphylococcal Infections / Q000276:immunology*
chemical_list: D015415:Biomarkers