The Correlation Between the Subsets of Tumor Infiltrating Memory T Cells and the Expression of Indoleamine 2,3-Dioxygenase in Gastric Cancer

Although many researchers have concentrated on the mechanism of T cell anergy resulting from over-expression of Indoleamine 2,3-dioxygenase (IDO), it remains unclear what alterations will developed in memory T cells (Tm) under over-expression of IDO.

The higher IDO expressions were significantly associated with deeper invasion (P = 0.016) and higher frequencies (P = 0.038) of lymph node metastasis. The lower tumor-infiltrating CD4⁺Tm were significantly associated with the advanced clinical stage (P = 0.026) and lymph node metastasis (P = 0.016). The lower percentages of CD8⁺Tm were significantly related to undifferentiated histological type (P = 0.042) and lymph node metastasis (P = 0.037). However, the lower percentage of CD8⁺Tem was significantly correlated to differentiated histological type (P = 0.017), lower frequencies of lymph node metastasis (P = 0.014), and earlier clinical stage (P = 0.008). The higher IDO expression patients had significantly lower percentages of CD4⁺Tm (P = 0.012) and CD8⁺Tm (P = 0.033). Nevertheless, it was confirmed that the higher level of IDO expression correlated with higher percentages of CD8⁺Tm cells in univariate and multivariate analysis (P = 0.011).

IDO over-expression and Tm in tumor microenvironments were correlated with the disease stage and histological type of gastric cancer. Higher IDO expression was related to the lower percentage of CD4⁺Tm and CD8⁺Tm, whereas the higher level of IDO expression related with a higher percentage of CD8⁺Tem.