Modulatory effects of tumor-derived heat shock protein in DNA vaccination against nasopharyngeal carcinoma

Use of anti-idiotype antibody vaccines is a promising strategy against tumor, however, their immunogenicity still need to be improved. Heat shock proteins (HSPs) have been shown to act as adjuvants when coadministered with peptides or given as fusion proteins and enhance the vaccination efficiency. To evaluate the enhancement of the potency of anti-idiotype antibody immunogenicity by heat shock protein gp96, C57BL/6 mice were immunized with three intramuscular inoculations of the G22 DNA and/or gp96 DNA vaccine. Control was inoculated with empty plasmid pcDNA3.1. The levels of G22-specific antibody and lymphocyte phenotype were measured by ELISA, fluorescence activated cell sorter (FACS) analysis, respectively. In the tumor protection experiment, the immunized mice were then challenged with CMT-93-G22 cells. The tumor size and the survival time of the animals were compared among these groups. The results showed that the efficacy of G22 DNA vaccine could be enhanced by coadministrating with gp96 DNA which might be relevant with activating CD8(+)T cells. Furthermore, co-injection of G22 DNA with gp96 DNA could prolong the survival time and lessen the tumor size of the CMT-93-G22-bearing mice. Our study demonstrates for the first time that G22+gp96 DNA vaccine can induce comparable G22-specific CD8(+)T cell response and is a promising candidate DNA vaccine for nasopharyngeal carcinoma. (C) 2011 Elsevier B.V. All rights reserved.