HER2 peptide-specific CD8+ T cells are proportionally detectable long after multiple DNA vaccinations

K Mukai, Y Yasutomi, M Watanabe, A Kenjo, T Aota… - Gene therapy, 2002 - nature.com
K Mukai, Y Yasutomi, M Watanabe, A Kenjo, T Aota, L Wang, H Nishikawa, M Ishihara…
Gene therapy, 2002nature.com
We prepared a plasmid encoding 147 amino acid residues from the N terminus of c-erbB-
2/HER2/neu (HER2), which included both a cytotoxic T lymphocyte (CTL) epitope
(HER2p63) and a helper epitope (HER2p1), using the mammalian expression vector
pCAGGS-New (pCAGGS147HER2). In a parallel analysis with a Tetramer assay and CTL
assay, good specificity and sensitivity of a quantitative enzyme-linked immunospot
(ELISPOT) assay to detect functional HER2p63-specific CD8+ T cells were demonstrated …
Abstract
We prepared a plasmid encoding 147 amino acid residues from the N terminus of c-erbB-2/HER2/neu (HER2), which included both a cytotoxic T lymphocyte (CTL) epitope (HER2p63) and a helper epitope (HER2p1), using the mammalian expression vector pCAGGS-New (pCAGGS147HER2). In a parallel analysis with a Tetramer assay and CTL assay, good specificity and sensitivity of a quantitative enzyme-linked immunospot (ELISPOT) assay to detect functional HER2p63-specific CD8+ T cells were demonstrated after intramuscular immunization of pCAGGS147HER2. In an ELISPOT assay for HER2p63, spots of IFNγ-producing cells were first detected 10 days after the first immunization, and additional immunizations increased the number of spots. HER2p63-specific CD8+ T cells were detected over a period of more than 10 months after the last immunization. In hosts receiving more than three immunizations, surprisingly high numbers of specific CD8+ T cells were persistently detectable. HER2 protein-specific antibodies of IgG class with dominance of IgG2a remain detectable 6 months after single or multiple immunizations. The antibodies however, were not reactive with cell surface HER2 antigens. Total suppression of tumor growth was observed when syngeneic HER2+ tumor cells (2× 10 6) were injected subcutaneously 14 days after a single immunization with pCAGGS147HER2. Furthermore, the number of pulmonary metastases decreased significantly when DNA vaccination was initiated on the day of, or 3 days after, intravenous injection (1× 10 6 cells).
nature.com