Induction of tumor-reactive CTL by C-side chain variants of the CTL epitope HER-2/neu protooncogene (369-377) selected by molecular modeling of the peptide: HLA-A2 complex.
To design side chain variants for modulation of immunogenicity, we modeled the complex of the HLA-A2 molecule with an immunodominant peptide, E75, from the HER-2/neu protooncogene protein recognized by CTL. We identified the side chain orientation of E75. We modified E75 at the central Ser(5) (E75 wild-type), which points upward, by removing successively the HO (variant S5A) and the CH2-OH (variant S5G). Replacement of the OH with an aminopropyl (CH2)3-NH3 (variant S5K) maintained a similar upward orientation of the side chain. S5A and S5G were stronger stimulators while S5K was a weaker stimulator than E75 for induction of lytic function, indicating that the OH group and its extension hindered TCR activation. S5K-CTL survived longer than did CTL induced by E75 and the variants S5A and S5G, which became apoptotic after restimulation with the inducer. S5K-CTL also recognized E75 endogenously presented by the tumor by IFN-gamma production and specific cytolysis. S5K-CTL expanded at stimulation with E75 or with E75 plus agonistic anti-Fas mAb. Compared with S5K-CTL that had been restimulated with the inducer S5K, S5K-CTL stimulated with wild-type E75 expressed higher levels of E75(+) TCR and BCL-2. Activation of human tumor-reactive CTL by weaker agonists than the nominal Ag, followed by expansion with the nominal Ag, is a novel approach to antitumor CTL development. Fine tuning of activation of tumor-reactive CTL by weak agonists, designed by molecular modeling, may circumvent cell death or tolerization induced by tumor Ag, and thus, may provide a novel approach to the rational design of human cancer vaccines.
Castilleja
Agapito
A
Department of Gynecologic Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
Carter
Darrick
D
Efferson
Clay L
CL
Ward
Nancy E
NE
Kawano
Kouichiro
K
Fisk
Bryan
B
Kudelka
Andrzej P
AP
Gershenson
David M
DM
Murray
James L
JL
O'Brian
Catherine A
CA
Ioannides
Constantin G
CG
D000276:Adjuvants, Immunologic / Q000138:chemical synthesis / Q000494:pharmacology; D000409:Alanine / Q000235:genetics; D019943:Amino Acid Substitution / Q000276:immunology*; D017951:Antigen Presentation; D000951:Antigens, Neoplasm / Q000276:immunology*; D017209:Apoptosis / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002448:Cell Adhesion / Q000276:immunology; D002460:Cell Line; D002470:Cell Survival / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D018734:Genes, erbB-2 / Q000276:immunology*; D005998:Glycine / Q000235:genetics; D015789:HLA-A2 Antigen / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008239:Lysine / Q000235:genetics; D008958:Models, Molecular; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology* / Q000494:pharmacology; D012694:Serine / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology*; D014407:Tumor Cells, Cultured
D000276:Adjuvants, Immunologic; D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; D010446:Peptide Fragments; D012694:Serine; D007371:Interferon-gamma; D008239:Lysine; D000409:Alanine; D005998:Glycine