The largest study was by Klingler et al of 126 patients with CRSsNP which identified that CXCL9 and CXCL10 were elevated in patients characterized by the T1 endotype compared to non-T1 CRSsNP and controls.40 Study quality was fair with detailed CRS inclusion criteria but nasal lavage fluid samples were highly diluted. Here, CXCL9 is linked to chronic rhinosinusitis without nasal polyps.