Evaluation of two different adjuvants with immunogenic uroplakin 3A-derived peptide for their ability to evoke an immune response in mice

Rationale: Organ- or tissue-specific antigens produced by normal tissue or by cancer cells could be used in cancer immunotherapy, to target the tumor. In our previous study, we induced T-cell-mediated, bladder-specific autoimmunity by targeting the bladder-specific protein Uroplakin 3A (UPK3A). UPK3A is a well-chosen target for developing an autoimmune response against bladder cancer since the antigen is also expressed in bladder tumors. To use this peptide, which was derived from the UPK3A protein in a bladder cancer vaccine study, it is necessary to induce a strong immune response. In this study, we aimed to develop a robust immune response in BALB/c mice using the well-characterized keyhole limpet hemocyanin (KLH)-conjugated peptide antigen (UPK3A 65-84) conjugated with an immunogenic carrier protein. In combination with the peptide, we used either Freund's complete adjuvant (CFA) or CpG (cytosine-phosphate-guanine oligonucleotides) as effective adjuvants in order to overcome tumor tolerance. Objectives: The immune response evoked by UPK3A 65-84 peptide, using two different adjuvants, was compared by detection of changes in the proliferative response of immune cells, in the cytokine profile, and in the immune cell populations. Findings: We demonstrated that CpG, combined with KLH-UPK3A 65-84, promoted a more robust immune response, via induction of higher IL-2, IFN-gamma, TNF-beta, IL-17 production and activation of more immune cells (CD4(+) T cells, CD8(+) T cells, NK cells CD11b, CD45), than CFA and the KLH-UPK3A 65-84. Conclusion: CpG as an adjuvant combined with KLH-UPK3A 65-84 could be used in preclinical models of bladder cancer for the development of cancer immunotherapy strategies