Cellular immune recognition of HLA-A*0201 following gene transfer into a human embryonal carcinoma cell line

Previously, we have established that transcription and cell surface expression of MHC class I and beta 2m genes in undifferentiated Tera-2 stem cells, a teratocarcinoma-derived cell line, was extremely low. In this study, we have transfected an HLA-A*0201-encoding cDNA driven by the CMV-promoter into Tera-2 cells. Prior to IFN gamma treatment, membrane expression of HLA-A*0201 by these Tera-2 transfectants was nearly lacking. Consequently, the HLA-A*0201 Tera-2 transfectants were not recognized by the allo-HLA-A*0201-specific CTL clone 3E7. Following IFN gamma treatment, which resulted in upregulation of HLA-A*0201, Tera-2 cells were lysed by CTL clone 3E7. In contrast, loading of HLA-A*0201 with the influenza-A-matrix peptide 58-66 resulted in partial lysis of Tera-2 cells by the influenza-A-matrix protein-specific CTL clone Q66-9, and nearly complete lysis was observed following IFN gamma treatment. These results suggest that the HLA-A*0201 transgenes in Tera-2 cells can be loaded with peptides and used as targets for peptide-specific CTLs.