Tumor cells often have aberrant post-translational modifications of their proteins. In bladder cancer, one of these modifications is the sialyl-Tn (STn) glycan, which is not expressed by normal cells and is highly expressed in high-grade bladder cancer cells. It is known that the immune response is affected by tumor cells, promoting tumor progression. However, little is known about the role of STn in the immune response and its influence on immune cells. Dendritic cells (DCs) play a crucial role in the immune response against tumor cells.