Influence of nasal polyp tissue on the differentiation and activation of T lymphocytes in a co-culture system.

T cell subpopulations in nasal polyps differ from peripheral lymphocytes in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). However, little is known about the modulatory influence of the inflamed nasal polyp epithelial cells on the phenotype of the T cells. The aim of the present study was to assess this interaction. Tissue and blood samples were collected from 16 patients undergoing paranasal sinus surgery. Polypoid tissue was cultured under air-liquid interface conditions. Subsequently, cluster of differentiation (CD)3/CD28 activated peripheral lymphocytes from the same patients were added. After 3 days lymphocytes were separated from co-culture and analyzed by multicolor flow cytometry. Additionally, cytokine expression of the polyp tissue was measured using a human T helper cell (TH)1/TH2/TH17 antibody array. Viability staining of CD3+ lymphocytes detected fewer apoptotic cells under co-culture conditions compared with in mono-culture. There was a significantly higher frequency of CD4+ and CD8+ T cells in the co-culture system than in PBMC culture alone. Human leukocyte antigen (HLA)-DR isotype was significantly downregulated on co-cultured CD3+ lymphocytes and CD3+CD4+ T cells compared with the mono-cultured counterparts. Conventional Forkhead box P3- memory CD4+ T cells and activated regulatory T cells increased in frequency, and resting regulatory T cells decreased in the co-culture. Cytokine analysis identified expression of interleukin (IL)-6, IL-6 receptor, granulocyte-macrophage colony-stimulating factor, transforming growth factor-β and macrophage inflammatory protein-3 in the polyp tissue. In summary, the present study performed a comparison between peripheral lymphocytes cultured with and without nasal polyp tissue cells was performed. The downregulation of HLA and the differentiation of Treg and Tconv by nasal polypoid tissue on PBMCs was demonstrated. Interestingly, the in vivo downregulation of HLA-DR on CD3+ lymphocytes, as reported previously, was confirmed in vitro. The inhibitory effect of polypoid tissue on the activation of lymphocytes is a possible pathogenic mechanism underlying CRSwNP.