The present invention provides improved vaccine compositions having enhanced immunogenicity and methods of using same. The compositions and methods include immunogenic conjugates containing peptide carriers derived from heat shock protein 60 (HSP60). The known synthetic peptide carrier, p458, provides significantly improved immunogenicity when provided as a multimeric conjugate comprising a plurality of peptide carrier units conjugated to each antigen. Cell vaccine compositions comprising antigen presenting cells loaded with multimeric p458 conjugates are also provided.