A cell-based vaccine composed of previously frozen autologous antigen-presenting peripheral blood mononuclear cells (enriched for a dendritic cell fraction) that have been exposed to a recombinant protein consisting of granulocyte-macrophage colony-stimulating factor (GM-CSF) fused to prostatic-acid phosphatase (PAP), a protein expressed by prostate cancer cells. Upon administration, the vaccine may stimulate an antitumor T-cell response against tumor cells expressing PAP.