An entirely carbohydrate-based immunogen consisting of a zwitterionic polysaccharide (ZPS) PS A1 and the well-known tumor antigen Tn has been designed, synthesized, and studied for immunological effects. The PS A1 motif was included to act as an MHCII elicitor for a T-cell-dependent immune response with increased immunogenicity against tumor-associated carbohydrate antigens, providing an alternative to carrier proteins. Through the use of C57BL/6 mice, it has been shown that chemical modification of PS A1 does not alter the recognition sequence responsible for an MHCII-mediated, T-cell-dependent immune response. The Tn-PS A1 conjugate construct confers specificity toward the Tn antigen alone, and specific carbohydrate immunoglobulins, namely, IgG3, are generated from intraperitoneal immunizations with or without adjuvant. The properties of the vaccine candidate are attributed to a site-specific linking strategy that incurs significant incorporation of Tn antigen.