Enhancement of cytolytic T lymphocyte precursor frequency in melanoma patients following immunization with the MAGE-1 peptide loaded antigen presenting cell-based vaccine.

Identification of human melanoma-associated peptide antigens for CTLs has opened unprecedented opportunities for active specific immunotherapy for melanoma with synthetic peptide. We have shown that immunization with a MAGE-1 gene encoded nonapeptide (EADPT-GHSY)-pulsed autologous antigen presenting cell-based vaccine induces autologous melanoma-reactive and peptide-specific CTL response, in situ, at the vaccination site and at distant tumor deposits in patients who are HLA-A1+ and whose melanoma cells express the MAGE-1 mRNA. Here, we show that such immunization is also capable of increasing the frequency of autologous melanoma-reactive CTL precursors in the circulation. We further show that in vitro stimulation of the postimmunization peripheral blood lymphocytes with the MAGE-1 nonapeptide-loaded antigen presenting cell and interleukin-2 leads to significant expansion of peptide-specific and autologous melanoma-reactive CTL response.