IL17A and pneumococcal infection: In a mouse model, Streptococcus pneumonia infection in infancy increased the risk of adulthood allergic airway diseases, with elevated Th17/IL-17 levels and accumulation of neutrophils, whereas the neutralization of IL-17 by monoclonal antibody significantly reduced neutrophil recruitment, alleviated airway inflammation, and decreased airway hyperresponsiveness, indicating an essential role of IL-17 in the pathogenesis of neutrophilic asthma [67].