An immunodominant SSX-2–derived epitope recognized by CD4⁺ T cells in association with HLA-DR
J. Clin. Invest. Maha Ayyoub, et al. 113:1225 doi:10.1172/JCI20667 [Go to this article.]

Figure 5
SSX-2–specific CD4⁺ T cells do not directly recognize SSX-2–expressing tumor cells. (A) Surface expression of HLA-DR on the melanoma cell line T567A was assessed using HLA-DR–specific mAb. (B) Recognition of T567A by SSX-2–specific CD4⁺ T cells was assessed by intracellular staining with anti–IFN-γ antibodies, in the absence or the presence of exogenously added peptide. Where indicated, cells were treated with IFN-γ (200 IU/ml) for 48 hours. Recognition was similarly assessed using a CD8⁺ T cell clone specific for the previously described HLA-A2–restricted CD8⁺ T cell epitope SSX-2_41–49. PerCP, peridinin chlorophyll protein. (C) Recognition of melanoma cell lines by SSX-2–specific CD4⁺ or CD8⁺ T cells, in the absence or the presence of exogenously added peptide, as indicated, was assessed by ELISA measurement of IFN-γ secretion in the culture supernatant. Prior to the test, tumor cells were treated with IFN-γ for 48 hours. Where indicated, tumor cells were transfected with a plasmid encoding full-length SSX-2. *The Me 279.1 tumor cell line had no surface expression of MHC class I molecules as assessed by staining with anti–HLA-ABC mAb.