In the setting of pneumococcal pneumonia, TH17 TRM cells, via secretion of IL-17A, instigate enhanced secretion of CXCL5 from lung epithelial cells to enforce rapid neutrophil recruitment and anti-bacterial immunity.41,63 Our current study extends this cell signaling axis to allergic airway neutrophilia and suggests that CXCL6 (the human ortholog of murine CXCL5) might be a good biomarker for neutrophilic asthma. This evidence concerns the gene IL17A and pneumococcal pneumonia.