[Expression of Type 2 Innate Lymphoid Cell and IL-9 and Other Related Cytokines in Chronic Lymphocytic Leukemia]

To explore the difference of type 2 innate lymphoid cell (ILC2), IL-9 and related cytokines between chronic lymphocytic leukemia (CLL) patients and normal individuals, as well as the correlation between ILC2 and IL-9 and other cytokines in CLL patients.

Flow cytometry was used to detect the expression of ILC2 and regulatory T cells (Tregs) in peripheral blood of 26 CLL patients at initial diagnosis and 10 healthy controls. RT-qPCR was used to detected IFN-γ, TGF-β, IL-9 and IL-10 mRNA in peripheral blood mononuclear cell (PBMC). ELISA was used to detect serum IFN-γ, TNF-α, TGF-β, IL-9, IL-10 and IL-21. ILC2 and IL-9 were observed in the cervical lymph node of 12 CLL patients at initial diagnosis and 12 patients with reactive lymphoid hyperplasias by multiplex indirect immunofluorescence staining. Spearman test was used to analyze the correlation between peripheral blood ILC2 and IL-9, IL-9 and IL-21, IFN-γ mRNA and IL-10 mRNA in CLL patients. Pearson test was used to analyze the correlation between TNF-α and TGF-β in CLL patients.

Compared with control group, the proportions of ILC2 and Tregs were significantly increased in CLL group (both P < 0.05). The mRNA expressions of IFN-γ, IL-9, IL-10 and TGF-β in PBMCs of CLL patients were significantly increased (all P < 0.05). In CLL patients, the expressions of IFN-γ, TNF-α, TGF-β, IL-9 and IL-10 in serum were significantly increased (all P < 0.01), while IL-21 slightly increased without statistical difference (P >0.05). In CLL patients, the peripheral blood ILC2 was positively related to IL-9 (r =0.56), IL-9 was positively related to IL-21 (r =0.397), IFN-γ mRNA was positively related to IL-10 mRNA (r =0.623), and TNF-α was positively related to TGF-β (r =0.577). Compared with reactive lymphoid hyperplasias patients, the mean fluorescence intensities of GATA3 and CRTH2 representing ILC2 and IL-9 in cervical lymph nodes were significantly increased in the CLL group (all P < 0.001), and showed colocalization.

In CLL patients, the proportions of ILC2 and IL-9 in peripheral blood and lymph nodes increase, and ILC2 and IL-9 show colocalization in lymph nodes. There is a positive correlation between ILC2 and IL-9 in the peripheral blood of CLL patients, the ability of ILC2 to secrete IL-9 is increased, and ILC2 may affect the occurrence and development of CLL through IL-9.