HER2 peptide-specific CD8(+) T cells are proportionally detectable long after multiple DNA vaccinations.
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 IFN gamma-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 x 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 x 10(6) cells).
Mukai
K
K
Second Department of Internal Medicine, Mie University School of Medicine, Tsu, Mie, Japan.
Yasutomi
Y
Y
Watanabe
M
M
Kenjo
A
A
Aota
T
T
Wang
L
L
Nishikawa
H
H
Ishihara
M
M
Fujita
T
T
Kuribayashi
K
K
Shiku
H
H
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D018984:Epitopes, T-Lymphocyte / Q000235:genetics*; D005260:Female; D018734:Genes, erbB-2; D015316:Genetic Therapy / Q000379:methods*; D007115:Immunization Schedule; D007074:Immunoglobulin G / Q000276:immunology; D007273:Injections, Intramuscular; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D013997:Time Factors; D019444:Vaccines, DNA / Q000008:administration & dosage*
D018984:Epitopes, T-Lymphocyte; D007074:Immunoglobulin G; D018719:Erb-b2 Receptor Tyrosine Kinases; D019444:Vaccines, DNA