Tim-3 expression predicts the abnormal innate immune status and poor prognosis of glioma patients

Malignant glioma, the most common and devastating primary brain tumor, has serious effects on human health with high risk of recurrence and short survival periods. Recently, the exploitation of immunological mechanisms shed new lights for developing novel therapeutic strategies for glioma pathogenesis. Tim-3, a member of T cell immunoglobulin and mucin domain family, has been involved in multiple diseases, including tumor, by regulating the viability and function of immunocytes. In the present study, we detected Tim-3 expression on peripheral innate immunocytes from glioma patients and analyzed their correlation with clinical indices. We found that the number of CD3^-CD56⁺ NK cells decreased in glioma patients. Compared with healthy controls, glioma patients had higher Tim-3 expression on peripheral CD3^-CD56⁺ NK cells and CD14⁺ monocytes. Tim-3⁺ NK cells had decreased capability of IFN-r secretion, while Tim-3⁺ monocytes showed a M2-like phenotype. Importantly, Tim-3 level on both NK cells and monocytes positively correlated with the ratio of Ki-67⁺ tumor cells. Moreover, patients with high percentage of Tim-3⁺ monocytes showed high risk of recurrence or death. Our present work gives new insights into the innate immune mechanisms in glioma and might provide new evidences for the clinical practice of Tim-3-based immunotherapy in glioma.