NK cells in patients with chronic rhinosinusitis show decreased maturity and limited expression of functional receptors.

Chronic rhinosinusitis is an inflammatory process of the mucous membrane of the nasal cavity and paranasal sinuses, presenting with two phenotypes that differ in symptoms and inflammatory profiles: either with or without polyps. Natural killer (NK) cells are involved in both the innate and acquired immune response, and their function may be limited under pathological conditions, leading to polyp formation. We determined NK cell involvement and maturity in chronic rhinosinusitis, by determining the percentage of NK cells in polyps, nasal mucosa, and in the peripheral blood. Material was obtained from 49 patients with chronic rhinosinusitis (36 with polyps, 13 without polyps), and 15 control patients. Flow cytometry was used to immunophenotype NK cells, and the expression of selected functional receptors was evaluated. NK cells were found to be increased in polyp tissue versus peripheral blood and nasal mucosa. NK cell maturation differed significantly with predominance of a cytotoxic phenotype (CD11b+/27-) in peripheral blood, compared with a regulatory/tolerogenic phenotype (CD11+/-/ 27+) in tissue material. These findings demonstrate the involvement of NK cells in the inflammatory process of chronic rhinosinusitis. Decreased expression of activating receptors in the analyzed groups may also indicate the presence of modifying agents. Disorders of the maturation process of NK cells may be an important element in the etiopathogenesis of chronic rhinosinusitis with and without polyps.