Synthetic peptides induce a cytotoxic response against human papillomavirus type-18.
OBJECTIVE
Over 90% of cervical carcinomas express human papillomavirus (HPV) E6 and E7 proteins. These unique antigens are ideal targets for the development of cytotoxic T-lymphocytes (CTL) for antitumor immunotherapy. In this study we identify peptides from HPV-18 E6 and E7 proteins that bind to HLA class I molecules. We further show that these peptides are able to induce peptide-specific CTL from an HLA-A2-positive (+) peripheral blood donor in vitro.


METHODS
A computer-assisted algorithm was devised to identify peptides from HPV-18 E6 and E7 proteins that bind to HLA-A2 molecules. Peptides that were predicted to bind were synthesized and their binding activity was determined. HLA-A2(+) irradiated stimulator cells pulsed with HPV-18 peptides were incubated with HLA-A2(+) peripheral blood mononuclear cells. Cytotoxicity assays were performed to assess specific cell lysis.


RESULTS
Of 295 possible sequences, the computer-assisted algorithm predicted 10 peptides that would have a high probability of binding to HLA-A2. The 4 strongest binding peptides were analyzed for their ability to induce cytotoxic cells against HPV-18 peptide-pulsed targets. Two of the peptides induced significant lysis.


CONCLUSIONS
There are limited data on peptide-based immunotherapy for HPV-18(+) tumors. The combination of our computer-assisted algorithm and binding assay permits rapid selection of potential CTL epitopes. We identified two peptides that were able to induce peptide-specific lysis. These two epitopes are candidates for a peptide-based vaccine against HPV-18(+) tumors. The model described has broad applications and can be used in the development of immunotherapy for other types of cancers.
Castellanos
M R
MR
Department of Medicine, Nalitt Institute for Cancer and Blood Related Diseases, Staten Island, New York, 10305, USA.
Hayes
R L
RL
Maiman
M A
MA
D001665:Binding Sites; D002460:Cell Line; D002478:Cells, Cultured; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic; D004268:DNA-Binding Proteins; D015789:HLA-A2 Antigen / Q000276:immunology; D006801:Humans; D020014:K562 Cells; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D009856:Oncogene Proteins, Viral / Q000138:chemical synthesis / Q000276:immunology*; D027383:Papillomaviridae / Q000276:immunology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; C052633:E7 protein, Human papillomavirus type 18; D015789:HLA-A2 Antigen; D009856:Oncogene Proteins, Viral; D010446:Peptide Fragments