HPV16 E6 29-38-specific T cells kill cervical carcinoma cells despite partial evasion of T-cell effector function.
Persistent human papillomavirus type 16 (HPV16) infection is associated with the development of more than 50% of cervical cancers. The HPV16 E6 and E7 oncoproteins are constitutively expressed in cervical carcinomas and are attractive targets for cytotoxic T lymphocyte (CTL)-based immunotherapy. However, cervical carcinomas may possess multiple evasion mechanisms for HPV16 E6/E7-specific CTL. In this study, we investigated whether HPV16(+) cervical carcinoma cell lines (CaCxCL) could evade all effector functions of HPV16 E6(29-38)-specific T cells. Such CD8(+) T cells were detected in the blood (4/10) or invaded lymph node (1/1) of cervical cancer patients using HLA-A*0201/HPV16 E6(29-38) tetramers after in vitro stimulation. T cells cultured from 3 different donors killed HPV16 E6(29-38) peptide-pulsed target cells but not HPV16(+) CaCxCL in (51)Cr release assays. The absence of killing correlated with limited T-cell degranulation against CaCxCL, but this was not due to antigen processing defects per se; CaCxCL could induce specific T-cell release of IFN-gamma and TNF-alpha, and CaCxCL could be killed in longer cytotoxicity assays (>20 hr). Interestingly, the 'slow' killing of CaCxCL could be partially inhibited by concanamycin A, a known perforin inhibitor. The results suggest that CaCxCL was only partially activating T cells, but this was still sufficient for slow killing. Overall, our results highlight the need to examine multiple T-cell effector functions in the context of endogenous antigen presentation by tumour cells. In this study, testing for cytotoxicity using short-term assays only would have ruled out a candidate epitope for immunotherapy.
Thomas
Karen J
KJ
Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Henry Wellcome Building, Heath Park, Cardiff, United Kingdom.
Smith
Kelly L
KL
Youde
Sarah J
SJ
Evans
Mererid
M
Fiander
Alison N
AN
Borysiewicz
Leszek K
LK
Man
Stephen
S
D016022:Case-Control Studies; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D009856:Oncogene Proteins, Viral / Q000276:immunology*; D012097:Repressor Proteins / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D002583:Uterine Cervical Neoplasms / Q000276:immunology*
C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins