Detection of tumor-specific T cells infiltrating primary UMs. (A) Example of dual color staining of Melan-A–specific CD8⁺ T cells in juxta-tumor and tumor tissues. (B) Frequency of HLA-A2:Melan-A-tetramer–positive cells in CD8⁺ T cells in juxta-tumor and tumor tissues. (C) Representative dot plot of HLA-A2:pp65 CMV–specific CD8⁺ T cells. (D) Frequency of HLA-A2:CMV-tetramer–positive CD8⁺ T cells in juxta-tumor and tumor samples. (E and F) Example of PD-1 and CD39 expression in tetramer⁺CD8⁺ T cells in juxta-tumor and tumor tissues. (E) HLA-A2:Melan-A-tetramer–positive CD8⁺ T cells. (F) HLA-A2:CMV-tetramer–positive CD8⁺ T cells. (G) Frequency of tetramer-positive CD8⁺ T cells expressing both CD39 and PD-1 in tetramer-positive cells in the juxta-tumor and tumor tissues. (H) Frequency of HLA-A2:Melan-A-tetramer–positive cells in CD8⁺ T cells infiltrating D3 or M3 tumors. (I)MLANA gene expression (RNAseq) in 24 D3 and 49 M3 enucleated primary UMs. (J) Examples of immunohistochemistry for Melan-A and MHC class I in a representative case of D3 and M3 UM, respectively. Scale bars, 25 μm. (K and L) Results of semiquantitative evaluation of Melan-A (K) and MHC class I (L) immunostaining in tumor cells in D3 and M3 UM expressed as H-score (median, 95% CI). Coh1 (n = 20) and coh4 (n = 4) were used in A–H. Independent UM cohorts for J–L. ND: not detected. N/A: not applicable; the phenotype was not calculated when less than five tetramer⁺ cells were detected. Non-parametric paired Wilcoxon or unpaired Mann–Whitney tests were used as appropriate.