Upregulated Expression of Indoleamine 2, 3-Dioxygenase in Primary Breast Cancer Correlates with Increase of Infiltrated Regulatory T Cells In Situ and Lymph Node Metastasis

Figure 2

IDO expression in PTs was positively correlated with the density of Tregs in PTs and TDLNs. The Foxp3⁺ Tregs in PTs, TDLNs, benign disease, and normal adjacent tissues were detected using IHC staining method. (a)–(c) The Foxp3 protein appeared in the nuclei of lymphocytes infiltrated into PTs (a) and TDLNs, including nonmetastatic TDLNs (b) and metastatic TDLNs (c). (d)–(i) In the PTs with higher expression of IDO (d), more Foxp3⁺ Tregs infiltrated into the PTs (e) and corresponding TDLNs (f). In contrast, in the PTs with lower or no expression of IDO (g), less Foxp3⁺ Tregs were detected in the PTs (h) and corresponding TDLNs (i). (j) and (k) Scatter plots were generated to display the correlation between IDO expression in breast cancer (IDO⁺SIs in primary tumors) and the density of Foxp3⁺ Tregs in PTs (Foxp3⁺SIs in primary tumors) or in TDLNs (Foxp3⁺SIs in TDLNs). The IDO⁺SIs displayed a positive correlation with the Foxp3⁺ SIs in PTs with a linear regression equation of 𝑌 = 0.832 + 0.140 𝑋 (j). Accordingly, the IDO⁺SIs showed a similarly positive correlation with the Foxp3⁺ SIs in TDLNs with a linear regression equation of 𝑌 = 3.771 + 0.160 𝑋 (k).

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