Dendritic Cells Infected with a Vaccinia Vector Carrying the Human gp100 Gene Simultaneously Present Multiple Specificities and Elicit High-Affinity T Cells Reactive to Multiple Epitopes and Restricted by HLA-A2 and -A3

Abstract

To investigate the ability of human dendritic cells (DC) to process and present multiple epitopes from the gp100 melanoma tumor-associated Ags (TAA), DC from melanoma patients expressing HLA-A2 and HLA-A3 were pulsed with gp100-derived peptides G9154, G9209, or G9280 or were infected with a vaccinia vector (Vac-Pmel/gp100) containing the gene for gp100 and used to elicit CTL from autologous PBL. CTL were also generated after stimulation of PBL with autologous tumor. CTL induced with autologous tumor stimulation demonstrated HLA-A2-restricted, gp100-specific lysis of autologous and allogeneic tumors and no lysis of HLA-A3-expressing, gp100+ target cells. CTL generated by G9154, G9209, or G9280 peptide-pulsed, DC-lysed, HLA-A2-matched EBV transformed B cells pulsed with the corresponding peptide. CTL generated by Vac-Pmel/gp100-infected DC (DC/Pmel) lysed HLA-A2- or HLA-A3-matched B cell lines pulsed with the HLA-A2-restricted G9154, G9209, or G9280 or with the HLA-A3-restricted G917 peptide derived from gp100. Furthermore, these DC/Pmel-induced CTL demonstrated potent cytotoxicity against allogeneic HLA-A2- or HLA-A3-matched gp100+ melanoma cells and autologous tumor. We conclude that DC-expressing TAA present multiple gp100 epitopes in the context of multiple HLA class I-restricting alleles and elicit CTL that recognize multiple gp100-derived peptides in the context of multiple HLA class I alleles. The data suggest that for tumor immunotherapy, genetically modified DC that express an entire TAA may present the full array of possible CTL epitopes in the context of all possible HLA alleles and may be superior to DC pulsed with limited numbers of defined peptides.

Biased epitope selection by recombinant vaccinia-virus (rVV)-infected mature or immature dendritic cells

“…In addition, we observed that the reactivity elicited against MART-1 was almost exclusively limited to the HLA-A*0201-associated MART-1:27-35 epitope, suggesting that the immunogenicity of a protein may not be necessarily expandable to multiple HLA alleles as desired by the whole Ag vaccination approach. Although others have reported successful induction of gp100-specific T cells using rVVinfected DC, 48,49 our parallel studies where induction of MART-1 reactivity was compared with that of gp100 using identical vectors demonstrated a much lower effectiveness of the gp100 construct to induce Ag-specific T cells in spite of identical efficiency of infection and expression of Ag (unpublished data).…”

“…46 An appealing tactic for Ag delivery includes the induction of Ag expression in DC to combine the pluripotentiality of whole Ag delivery with the costimulatory properties of these professional antigen-presenting cells. 7,[47][48][49][50] The success of these strategies is based on the assumption that the chances of a given molecule to be immunogenic are relatively uniformly distributed across the HLA polymorphism.…”

Priming of T cells with aAd-transduced DC followed by expansion with peptide-pulsed DC significantly enhances the induction of tumor-specific CD8+ T cells: implications for an efficient vaccination strategy

“…In agreement with our results, several groups demonstrated that virally transduced DC were able to prime Ag-specific CD8 + T cells in vitro. 23,26 Nevertheless, there was no direct comparison to the use of peptideloaded DC. In addition, most investigators used immature, peptide-pulsed or infected DC for priming and restimulation of CD8 + T cells.…”

“…In addition, most investigators used immature, peptide-pulsed or infected DC for priming and restimulation of CD8 + T cells. 22,23,[26][27][28][29] Philip et al showed that immature DC loaded with MART-1 peptide or infected with an adenoviral construct were functionally equivalent in the induction of peptide-specific CTL in vitro. 27 We have recently shown that peptide-pulsed immature DC are inferior to mature DC in inducing peptide-specific T-cell responses in vitro.…”

Immunogenicity of nonreplicating recombinant vaccinia expressing HLA-A201 targeted or complete MART-1/Melan-A antigen

“…5,20 Indeed, the few HLA -characterized peptides derived from tumor antigens might not represent the entire class -I and class -II presented epitopes profile. This potent diversity is underlined by the demonstrated capacity of the same antigen to generate differently restricted CTL 3,24,25 and by the observed capacity of patients with similar HLA haplotype, to respond differently to the same antigen. 17 Therefore, to design immunogenic reagents, one should carefully evaluate the characteristics and potentials of each antigen to define formulations with more efficient antitumor activity.…”