CD28 and neoplasm: We found that while CD73 expression in tumor-infiltrating CD28+CD8+ T cells was slightly upregulated compared to CD28+CD8+ T cells in the peripheral blood (MFI TIL/PBMC ratio = 1.61 ± 0.226), CD73 expression in CD28−CD8+ T cells isolated from tumor had significantly higher levels of CD73 than CD28−CD8+ T cells in the circulation (MFI TIL/PBMC ratio = 4.44 ± 0.822) (p < 0.0001) (Fig. 5c).