Role of gamma/delta T cell receptor-expressing lymphocytes in cutaneous infection caused by Staphylococcus aureus

Abstract

SUMMARY The high number of γ/δ-expressing T cells found in the epithelial lining layer suggests that they form a first line of defence against invading pathogens. To evaluate the role of γ/δ T cell-receptor (TCR)-expressing cells in cutaneous infection caused by Staphylococcus aureus, mice lacking γ/δ-expressing T cells (TCRδ−/−) were inoculated intradermally with S. aureus, and compared with S. aureus-infected congeneic TCRδ+/− control mice. The number of bacteria recovered from the skin of TCRδ−/− mice was significantly higher (P = 0·0071) at early time-points after inoculation compared to the number of bacteria isolated from infected TCRδ+/− congeneic controls. Nevertheless, inflammatory responses measured as serum IL-6 levels, were significantly lower in TCRδ−/− mice than in the control group. A possible explanation for this discrepancy was the observation of significantly decreased overall numbers of infiltrating cutaneous T lymphocytes, which are important producers of IL-6. These results support the notion that the γ/δ-expressing T cells that reside at the epithelial lining layer of the skin is of importance for early containment of the bacteria, thereby limiting their replication and spread.