Role of gamma-delta T cells in host response against Staphylococcus aureus-induced pneumonia

Background: Staphylococcus aureus is the major cause of hospital-acquired and community-acquired pneumonia. Host defense to S. aureus infection is largely mediated by the innate immune system. gamma delta T cells play an important role in innate immunity to many infectious diseases. However, less is known about the role of these cells during S. aureus-induced pneumonia. In this study, we examined the response and the role of gamma delta T cells to pulmonary S. aureus infection. Results: Mice infected with S. aureus intranasally showed rapid gamma delta T cells accumulation in the lung. Deficiency of gamma delta T cells led to attenuated bacterial clearance and less tissue damage in lung compared with WT mice. Moreover, TCR-delta(-/-) mice exhibited impaired neutrophil recruitment and reduced cytokine production at the site of infection. The gamma delta T cells in response to pulmonary S. aureus infection mainly secreted IL-17 and gamma delta T cells deficiency reduced IL-17 production, which might regulate the production of neutrophil-inducing cytokine/chemokine in the S. aureus-infected lungs. Conclusions: Accumulation of gamma delta T cells in the lungs to S. aureus infection is beneficial for bacteria clearance and also contributes to the tissue damage. These cells were the primary source of IL-17, which might influence the recruitment of neutrophils at the early stage of infection.