Expression of PD-1 on CD4+ Tumor-Infiltrating Lymphocytes in Tumor Microenvironment Associated with Pathological Characteristics of Breast Cancer.

CD4+/PD-1+ or CD4+/PD-1- tumor-infiltrating lymphocytes showed diverse association with pathological features of breast cancer. CD4+/PD-1+ tumor-infiltrating lymphocytes had a significant relationship with Ki-67 expression whereas CD4+/PD-1- tumor-infiltrating lymphocytes had a significant relationship with E-cadherin expression. Further studies are warranted to explore the immunomodulatory effects of phenotypes of CD4+ T cell subsets in breast cancer.