Chalk et al recently found that patients who developed pneumonia post‐operatively had decreased TLR4 expression in alveolar macrophages, suggesting that local cell‐mediated immunosuppression might be a risk factor for post‐operative pneumonia.30 TLR4 expression in alveolar macrophages in acute respiratory distress syndrome (ARDS) is suppressed, even after ex vivo stimulation to LPS.30 This evidence concerns the gene TLR4 and acute respiratory distress syndrome.