Circulating regulatory T cells (CD4+CD25+FOXP3+) decrease in breast cancer patients after vaccination with a modified MHC class II HER2/neu (AE37) peptide

Regulatory T cells (TReg), CD4+CD25+FOXP3+, are implicated in suppressing tumor immune responses. We analyzed peripheral blood lymphocytes (PBL) from breast cancer patients receiving a modified HLA class II HER2/neu peptide (AE37) vaccine for TReg cells and correlated their levels with vaccine-specific immune responses. The mean CD4+CD25+FOXP3+ TReg cells decreased in patients with vaccination with no significant difference in serum TGF-β levels. IFN-γ ELISPOT and DTH increased after vaccination with a good correlation between TReg cell reduction and size of DTH to AE37. The TReg cell reduction and associated immune response suggest that AE37 may be clinically useful.