Abstract:
Objective Myeloid-derived suppressor cells(MDSCs) are the important inhibitory immune cells in the tumor microenvironment that are directly involved in tumor immune escape and metastasis.This study aims to determine the distribution of CD33+MDSCs and regulatory T cells(Foxp3+Tregs) in breast cancer tissues, to detect IDO protein expression in CD33+ MDSCs, and to analyze the correlation between IDO expression in MDSCs and distribution of Foxp3 Tregs in breast carcinoma tissues, as well as their clinical significance.
Methods Paraffin-embedded samples were collected from 50 breast cancer patients who underwent surgery in Tianjin Medical University Cancer Institute and Hospital between January 2005 and January 2007.The distribution of CD33+ MDSCs and Foxp3+ Tregs in the breast cancer tissues of different stages was evaluated using immunohistochemical staining(IHC).The protein expression and cell localization of CD33 and Foxp3 were detected using the single-dye IHC method, whereas the IDO expression in the CD33+ MDSCs was detected using the double-dye IHC method.The correlation between IDO'MDSCs and Foxp3+Tregs in breast carcinoma samples and the relationship among the clinicopathologic features was analyzed.
Results The Foxp3 Tregs and CD33+MDSCs were sporadically distributed in the breast cancer tissues.The IDO expression levels in the MDSCs were closely correlated with axillary lymph node metastasis(P < 0.05). More Foxp3 + Tregs were observed in the cancer tissues with higher IDO expression levels in MDSCs compared with tissues with lower IDO expression levels(P < 0.05).
Conclusion IDO expression in MDSCs might benefit the recruitment of Tregs and promote the metastasis of breast cancer.