Wu J, et al. - Herein the authors assessed the association of proinflammatory cytokines within the olfactory cleft microenvironment with olfactory function in chronic rhinosinusitis. They also evaluated the expression of proinflammatory cytokines within the olfactory cleft microenvironment. Similar inflammatory microenvironment was found within the olfactory cleft and within the middle meatus. In CRS patients, the elevated levels of interleukin (IL)-2, IL-5, IL-6, IL-10, and IL-13 in olfactory cleft mucus were related to reduced olfactory identification scores. Deleterious effects could be produced by altered levels of select olfactory mucus cytokines on olfactory neuron function and turnover.