The Effect of Peptide Treatment on the HLA-Binding and Antibody Production in Peripheral Blood Mononuclear Cells Obtained from Japanese Breast Cancer Patients

Background: Our previous predictive peptide binding studies indicated that a novel 20-mer multiple antigen peptide, CH401MAP, containing an anti-human epidermal growth factor receptor 2 (HER2) monoclonal antibody epitope (N163-182), may potentially bind to more than 95% of class I human leukocyte antigens (HLAs) and to 30-50% of class II HLAs expressed on peripheral blood mononuclear cells (PBMCs). In this study, CH401MAP was used for in vitro stimulation of PBMCs obtained from Japanese breast cancer patients, and anti-CH401MAP antibody secretion was evaluated. Methods: PBMCs of breast cancer patients were stimulated with CH401MAP peptide in vitro. Eight days after stimulation, the culture supernatants were collected and the anti-CH401MAP antibody levels were determined using enzyme-linked immunosorbent assay. The correlation of the antibody level and HER2 expression level after in vitro stimulation was also evaluated. Results: CH401MAP specific antibody was detected in the culture supernatants of patients’ PBMCs after in vitro culture, irrespective of the peptide stimulation. The antibody levels of the three patient’s groups were significantly higher than that of HD group. Significant correlation was not observed between specific antibody production and cancer progression. Conclusion: The PBMC of Japanese breast cancer patients possessed the potential of anti-CH401MAP antibody secretion. The antibody secretion level was significantly higher than that of HD. It is correlated with the expression of HER2 on the cancer tissues but not with the HER2 level in the sera of patients.