This showed that infants with CF without the four key pathogens present in their lungs still show evidence of lung inflammation, characterised by the elevation of M-CSF, SDF-1alpha, IL-2, IL-12p40, IL-9, LIGHT/TNFSF14, IL-17 and MCP-1 in BAL (figure 4G). Here, IL17A is linked to cystic fibrosis.