Identification of a novel HLA-A*0201-restricted, cytotoxic T lymphocyte epitope in a human glioma-associated antigen, interleukin 13 receptor alpha2 chain.

PURPOSE

Interleukin 13 receptor alpha2-chain (IL-13Ralpha2) has been reported to be abundantly and specifically overexpressed in glioblastoma multiforme. Here we report the identification of a CTL epitope derived from the IL-13Ralpha2.

EXPERIMENTAL DESIGN

Mature dendritic cells (DCs) were pulsed with each of the synthetic peptides that were designed, based on a binding affinity-based prediction and a proteosomal cleavage site prediction system, and used to stimulate autologous CD8+ T cells from an HLA-A2+ healthy donor. After four to six cycles of restimulation, the immunoreactivity of the T cells was analyzed for specific IFN-gamma production and CTL reactivity.

RESULTS

Of the five peptides tested, IL-13Ralpha(345-354) (WLPFGFILI) induced a CD8(+) T-cell line that specifically produced IFN-gamma in response to HLA-A2+ T2 cells pulsed with the relevant peptide and lysed these cells. Peptide titration assays demonstrated that half-maximal lysis of IL-13Ralpha(345-354) peptide-reactive CD8(+) T cells required peptide loading concentration of approximately 5 nM. Perhaps most importantly, this CD8(+) T-cell line also displayed lytic activity against the HLA-A2+ human glioma cell lines that express IL-13Ralpha2.

CONCLUSIONS

This novel CTL epitope may therefore serve as an attractive component of peptide-based vaccines to treat glioma and as a surrogate marker of T-cell immune responses in patients before and after therapy.