Figure 4. Recognition of Epstein-Barr virus-transformed B cells (EBV-B cells) loaded with MAGEA3-expressing bacteria. The antigen-presenting cells (30,000/well) were EBV-B cells obtained from the Vogt-Konayagi-Harada (VKH) patient that also expressed human leukocyte antigen (HLA)-DP4 molecules. These cells were loaded with complement-opsonized bacteria, which expressed either MAGEA3 or Melan-A, as a negative control. As positive controls, we used cells loaded with another recombinant complement-opsonized bacteria producing MAGEA3 that was previously constructed in our laboratory, cells transduced with a retroviral construct encoding a truncated human invariant chain (Ii) fused with the MAGEA3 protein (retro-Ii.MAGEA3), or cells pulsed with MAGE-3.DP4 peptide ACYEFLWGPRALEVTS (24). In total, 5,000 cells of the anti-MAGE-3 T cell clone were added to each well. The amount of interferon (IFN)-γ secreted in the supernatant of the co-culture was measured by enzyme-linked immunosorbent assay (ELISA). The results shown represent an average of triplicate co-cultures. Error bars represent SD.