Vaccination with Recombinant NY-ESO-1 Protein Elicits Immunodominant HLA-DR52b-restricted CD4+ T Cell Responses with a Conserved T Cell Receptor Repertoire

Abstract

Purpose: ESO is a tumor-specific antigen with wide expression in human tumors of different histologic types and remarkable spontaneous immunogenicity. We have previously shown that specific T H 1 and antibody responses can be elicited in patients with no detectable preexisting immune responses by vaccination with rESO administered with Montanide ISA-51 and CpG ODN 7909. The purpose of the present study was to characterize vaccine-induced ESO-specific CD4 + Tcell responses. Experimental Design: We generated CD4 + T cell clones from patient C2, who had the highest CD4 + Tcell response to the vaccine, and analyzed their fine specificity and HLA class II restriction to determine the recognized epitope.We then assessed the response to the identified epitope in all vaccinated patients expressing the corresponding HLA class II allele. Results: We found that ESO-specific CD4 + T cell clones from patient C2 recognize peptide ESO 119-143 (core region 123-137) presented by HLA-DR52b (HLA-DRB3*0202), a MHC class II allele expressed by about half of Caucasians. Importantly, following vaccination, all patients expressing DR52b developed significant responses to the identified epitope, accounting for, on average, half of the total CD4 + T cell responses to the 119-143 immunodominant region. In addition, analysis of ESO-specific DR52b-restricted CD4 + T cells at the clonal level revealed significant conservation of T cell receptor usage among different individuals. Conclusions: The identification of a DR52b-restricted epitope from ESO that is immunodominant in the context of vaccine-elicited immune responses is instrumental for the immunologic monitoring of vaccination trials targeting this important tumor antigen.

Monitoring of NY-ESO-1 specific CD4 + T cells using molecularly defined MHC class II/His-tag-peptide tetramers

“…Whereas peptide ESO 123-137 was the minimal peptide optimally recognized by clonal CD4 + T cells, the ESO peptide originally used to identify the DR52b-restricted epitope was significantly longer, corresponding to the 25mer ESO 119-143 (9). We therefore synthesized DR52b/ESO 119-143 tetramers and assessed them on specific and control clonal populations.…”

“…We have previously reported that more than 50% of ESO-specific DR52b-restricted CD4 + T-cell clones isolated from vaccinated patients use Vβ2, suggesting a highly restricted TCR repertoire for T cells recognizing this epitope (9). To directly assess Vβ2 usage by tetramer-positive cells, we costained the cultures with tetramers and anti-Vβ2 specific antibodies.…”

“…Peripheral blood samples from healthy donors were obtained from the Etablissement Français du Sang Pays de la Loire (Nantes, France). MHC class II alleles were determined by high resolution molecular typing (9). ESO 119-143 -specific DR52b-restricted CD4 + T cell clonal populations were obtained from postvaccine samples as previously described (9).…”

“…MHC class II alleles were determined by high resolution molecular typing (9). ESO 119-143 -specific DR52b-restricted CD4 + T cell clonal populations were obtained from postvaccine samples as previously described (9). For assessment of specific CD4 + T-cell responses following in vitro stimulation, CD4 + cells were enriched from PBMC by magnetic cell sorting (Miltenyi Biotec Inc.), stimulated with irradiated autologous APC in the presence of a pool of overlapping long peptides spanning the ESO sequence, rhIL-2 and rhIL-7, as previously described (9), and maintained in culture for 10 to 15 days before tetramer staining.…”

“…In a recent vaccination trial using a recombinant ESO protein (rESO) administered with Montanide ISA 51 and CpG ODN 7909, we have observed induction of CD4 + T cell responses in all vaccinated patients (8). By assessing vaccineinduced CD4 + T cells, we have identified an immunodominant epitope (ESO , core region ESO [123][124][125][126][127][128][129][130][131][132][133][134][135][136][137] ) restricted by HLADR52b (DRB3*0202), an allele expressed by half of Caucasians (9). DRB3-, DRB4-, and DRB5-encoded molecules are less polymorphic than those encoded by DRB1, and are therefore attractive candidates for the development of generic MHC class II tetramers.…”