Peptide ID# Pulsed to T2-A24 Cells Supplemental Figure 1 HLA-A24 Median Fluorescence Intensity None HIV 1 2 3 4 5 6 7 1 2 3 4 1 2 3 4 5 6 7 1 2 3 4 5 6 XBP1 Unspliced XBP1 Spliced CD138 CS1 Peptide ID# Pulsed to T2-A24 Cells

XBP1 SP223-231 peptide-specific CTL Supplemental Figure 2 91% 8% 10% 0% CD3+CD8+ Gated CD3+CD8- IFN-g+ Cells Effector Cells: XBP1 SP223-231 peptide-specific CTL CD8+ CD8- CD3+ T cells SSC CD3 CD8 IFN-γ IFN-γ+

XBP1 SP223-231 peptide-specific CTL Supplemental Figure 3 Responder cells: XBP1 SP223-231 peptide-specific CTL Target cells: None KMS11 OPM1 LNCaP HLA-A24+ XBP1+ HLA-A24- XBP1+ HLA-A24+ XBP1- 6% 34% 6% 10% 17% 33% 20% CTL Proliferation : Day 5 CFSE low CFSE low 10% 74% 12% 18% CTL Proliferation : Day 7 CFSE low

XBP1 SP223-231 peptide-specific CTL Supplemental Figure 4 0.3% 4.6% 1.0% 0.7% 3.8% 0.5% % IFN-g+ /CD3+CD8+ T cells % IL-2+ % CD107a+ IFN-g+ Effector Cells: XBP1 SP223-231 peptide-specific CTL Target Cells  None HLA-A24+ KMS11 HLA-A24- OPM1 0.3% 25.4% 1.9% IFN-g CD107a IL-2 CD8 SSC IFN-g