Fig. 4.

MHC II uveal melanoma vaccines activate tumor-specific, CD8⁺ T cells that are cytolytic for MHC I-matched and -mismatched wild-type uveal melanoma targets. a HLA-A2,74⁺ DR1⁺ PBMC from a healthy donor were primed with MEL202/DR1/CD80 (HLA-A1,3⁺) vaccine cells, co-cultured with mAbs to CD107a and primary (MEL202, MEL270) or metastatic (OMM2.3) uveal melanoma targets, and subsequently labeled with mAbs to CD3 or CD8. CD3⁺CD8⁺ T cells were gated and analyzed for CD107a expression relative to primed PBMC cultured in the absence of target cells. b HLA-A2,A74⁺ DR1⁺ PBMC from a healthy donor were primed with MEL202/DR1/CD80 vaccine cells and tested for cytotoxic activity against ⁵¹Cr-labeled primary (MEL202, MEL270, MEL205: HLA-A2, 24⁺) or metastatic (OMM2.3) uveal melanoma or non-malignant human foreskin fibroblasts (HS68: HLA-A1,29⁺). PBMC were undepleted or depleted for CD8⁺ and CD56⁺ or CD56⁺ cells after priming and before the cytotoxic assay. CD56 and CD8 plus CD56-depleted PBMC contained <2 and 1% of CD8⁺ T cells and NK cells. Data for a are from one of three independent experiments. Data for CD56 and CD56 plus CD8 depletions of b are one of four and two independent experiments, respectively