In T-cell lines dually sensitized with antigens from EBV and CMV or from EBV and WT1 the T-cells specific for CMV or WT1 are often restricted by hla alleles that differ from those restricting T-cells specific for EBV

Abstract

Background & Aim Virus-specific T-cells generated from transplant or 3rd party donors can induce durable remissions of post-transplant severe infections or EBV lymphomas. T-cells simultaneously sensitized with antigens from multiple viruses have also shown promise. We hypothesized that in any individual donor, immunogenic peptides from different viruses might elicit T-cell responses restricted by different HLA alleles. In HLA non-identical patients, the T-cells, specific for one virus or tumor antigen will be effective only if they are restricted by an HLA allele shared by the patient. Methods, Results & Conclusion We analyzed HLA restrictions (HLA-R) of 42 CTL lines generated by dual sensitization with either autologous EBV-transformed B-cells (BLCL) loaded with a pool of overlapping 15-mer peptides spanning the sequence of CMVpp65 (BLCL/CMV CTL) (n=20) or autologous BLCL loaded with a pool of 15-mers spanning the oncofetal protein WT-1 (BLCL/WT1 CTL) (n=22). EBV CTL lines were generated by sensitization with BLCL alone. The HLA-R of the CMVpp65-specific T-cells(CMV-T), WT1 specific T cells (WT1-T) and EBV specific T cells (EBV-T) in each T cell product were assessed by their cytotoxic activity against a panel of Cr51 labeled peptide-loaded dendritic cells and BLCL sharing a single HLA allele with the T cell donor. In 13/20 BLCL/CMV CTL(65%) and 17/22 BLCL/WT1 CTL(77%) the CMV-T or WT1-T were restricted by single HLA alleles. In 10/20(50%) BLCL/CMV CTL, CMV-T and EBV-T in the same line were restricted by the same HLA allele. However, in the other 10(50%) the CMV-T were restricted by an HLA allele different from that of the EBV-T. Similarly, in 13/22(59%) BLCL/WT1 CTL, WT1-T and EBV-T in the same line were restricted by different HLA alleles. In 2/4 BLCL/CMV CTL and 2/5 BLCL/WT1 CTL, in which the HLA-R of CMV-T or WT1-T differed from that of EBV-T in the same culture, the HLA allele differentially presenting CMV or WT1 antigen but not an EBV antigen was a prominent restricting allele of EBV-T in the EBV CTL of the same origin. This suggests that while immunodominant EBV and CMV epitopes presented by certain prevalent HLA alleles such as HLA B0702 or HLA A0201 often induce responses to both viruses, in certain dual-sensitized cultures, immunogenic epitopes from different antigens may compete for presentation by a specific HLA allele or differ in their potential to induce a dominant T-cell response.