VDJ scRNAseq of T cells found in a primary M3 UM. CD3⁺ T cells isolated from an enucleated primary M3 UM tumor (coh4_84) were FACSorted into HLA-A2:Melan-A tetramer⁺ CD8⁺ T cells, HLA-A2:Melan-A tetramer^neg CD39⁺PD-1⁺CD8⁺ T cells, HLA-A2:Melan-A tetramer⁻CD39⁻ or PD-1⁻ CD8⁺ T cells, CD4⁺ T cells that were mixed in a 10, 30, 30, and 30% proportion, respectively, before analysis using the 10X VDJ 5′ scRNAseq technology. (A) UMAP of the scRNAseq dataset colored by inferred cluster identity. (B) Projection on the transcriptomic UMAP of the cells labelled by the HLA-A2:Melan-A tetramer⁺ cells (red). (C and D) Projection on the UMAP of the most expanded clonotypes (n ≥ 60 cells) corresponding to unlabeled (C, others) and labeled (D, HLA-A2:Melan-A) cells by the Melan-A tetramer. (E) Cluster of origin for cells expressing the most expanded clonotypes (n > 10 cells). Red stars indicate HLA-2A:Melan-A tetramer–specific clonotypes. (F) Distribution of the clonotype size in the different clusters. One clonotype can be represented in multiple clusters. (G) Clonal size of the expanded (n ≥ 2 cells) clonotypes in the different clusters.