Insertion signal sequence fused to minimal peptides elicits specific CD8+ T-cell responses and prolongs survival of thymoma-bearing mice.
CD8+ T-lymphocytes (TCD8+) recognize minimal peptides of 8-10 residues which are the products of intracellularly processed proteins and are presented at the cell surface by major histocompatibility complex class I molecules. An important step in this process is the translocation of processed proteins from the cytosol across the endoplasmic reticulum membrane, mediated by transporter associated with antigen-processing proteins or alternatively by endoplasmic reticulum-insertion signal sequences located at the NH2-terminus of the precursor molecules. We report here that the addition of an endoplasmic reticulum-insertion signal sequence at the NH2-terminus of TCD8+ epitopes from chicken ovalbumin (amino acids 257-264) or a naturally occurring tumor antigen expressed by the murine mastocytoma P815 (P1A amino acids 35-43) significantly enhanced the priming of specific TCD8+ in vivo. The signal sequence did not enhance peptide immunogenicity by merely increasing the hydrophobicity of the peptide, since ovalbumin amino acids 257-264 peptide with the signal sequence at its COOH-terminus did not demonstrate enhanced efficacy. The signal sequence did not act as a helper epitope, since TCD8+ responses were not diminished in class II-deficient transgenic mice or in mice depleted of CD4+ T-cells in vivo. Importantly, a single immunization with the fusion peptide significantly prolonged survival of mice challenged with E.G7OVA, a thymoma transfected with the complementary DNA of chicken ovalbumin.
Minev
B R
BR
Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland 20892.
McFarland
B J
BJ
Spiess
P J
PJ
Rosenberg
S A
SA
Restifo
N P
NP
D000595:Amino Acid Sequence; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000737:chemistry*; D000939:Epitopes / Q000276:immunology; D005260:Female; D007167:Immunotherapy / Q000379:methods*; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000627:therapeutic use*; D015398:Signal Transduction / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013945:Thymoma / Q000235:genetics / Q000276:immunology / Q000401:mortality / Q000628:therapy*; D013953:Thymus Neoplasms / Q000235:genetics / Q000276:immunology / Q000401:mortality / Q000628:therapy*; D014162:Transfection; D014407:Tumor Cells, Cultured
D000939:Epitopes; D011993:Recombinant Fusion Proteins; D010047:Ovalbumin