Human papillomavirus type 33 E7 peptides presented by HLA-DR*0402 to tumor-infiltrating T cells in cervical cancer

Abstract

Several characteristics make human papillomavirus (HPV) amenable to vaccination. Anti-HPV-directed vaccines are based on the observation that HPV E6 and E7 oncoproteins are constitutively expressed in HPV-positive cervical cancer and may serve as tumor rejection antigens. Five HPV types (16, 18, 31, 33, and 45) account for 80% of cervical cancer. Until now, the type of immune response capable of mediating an effective antitumor response has not been defined. In order to define the anticancer-directed immune response in situ, we characterized CD4(+) and CD8(+) sorted T cells from peripheral blood lymphocytes, freshly harvested tumor tissue, and tumor-infiltrating lymphocytes (TIL) from a patient with cervical cancer. The HLA-DR-restricted CD4(+) T-cell receptor VB16-, VA10-, VA21-, and VA22-positive CD4(+) T-cell line derived from TIL recognizes autologous HLA-DR*0402(+) (HPV33(+)) cervical cancer cells, as determined by gamma interferon secretion. Testing of different peptides spanning the E7 gene revealed that the HPV33(73-87) peptide ASDLRTIQQLLMGTV represents the immunodominant epitope which can also be presented by the DR*0401 allele to TIL. Such major histocompatibility complex class II-presented peptides represent attractive candidates to augment T-cell responses directed against autologous tumor cells.

Figures

FIG. 1

TCR VB families in PBL and TIL. PBL were gated on CD4+ or CD8+ T cells and tested for expression of individual TCR VB chains by flow cytometry. No major TCR VB expansion could be detected in PBL. In contrast, the majority of TIL (>98% CD4+) stained positive for the TCR VB16. +, detection of monoclonal TCR VB chains as listed in Table 2.

FIG. 2

Detection of TCR VB16+ T cells infiltrating into cervical cancer. Serial sections from tumor tissue were stained for CD3, CD4, CD8, and TCR VB16+ T cells. Note that CD4+ T cells represent the majority of T cells and that TCR VB16+ T cells directly infiltrate the tumor lesion.

FIG. 3

Titration of HPV33 E773–87 peptides onto autologous antigen-presenting cells. Peptides were serially diluted and pulsed onto antigen-presenting cells, incubated for 2 h at room temperature, and tested for CD4+ VB16+ T-cell recognition, as determined by IFN-γ secretion. The peptide ASDLRTIQQLLMGTV represents the dominant epitope.