The absolute numbers and percentage of Treg cells in the PB of healthy individuals and breast cancer patients was determined, and our data show that individuals with breast cancer have a significantly higher Treg frequency in the PB compared with healthy controls; Treg frequencies were >8% of CD4+ cells in breast cancer, compared with 6% of CD4+ cells in healthy controls (P<0.05). Here, CD4 is linked to breast carcinoma.