Expression of Inhibitory Natural Killer Receptors on Tumor-Infiltrating Cd8+ T Lymphocyte Lineage in Human Endometrial Carcinoma

To investigate the expression of natural killer receptors ( NKRs) within the human tumor milieu, we directly examined the in vivo expressions of various NKRs on tumor- infiltrating lymphocytes (TILs) derived from human endometrial carcinoma (EC). In total, 22 patients with stage IA–IIIA EC were enrolled. TILs were isolated from tissue specimens by means of a mechanical dispersal technique. The subpopulations of immunocytes were quantified, and expressions of NKRs on CD8+ T cells were analyzed by triple- color flow cytometry. CD8+ T cells express higher ratios of CD94 and NKG2A in TILs than in peripheral blood mononuclear cells (PBMCs) in human EC. Flow cytometry reveals that 15. 90% of CD3+CD8+ TILs compared with 2.10% of CD3+CD8+ PBMCs express the NKG2A molecules (P< 0.001). The percentage expressions of CD94 are 8.40% in CD3+CD8+ TILs and 3.80% in CD3 +CD8+ PBMCs (P= 0.013). The numbers of CD8+ T cells expressing CD158b and NKB1 are higher in CD3+CD8+ PBMCs in EC than in normal (CD158b: 10.70% vs 2.60%, P< 0.001; NKB1: 2.20% vs 0.40%, P= 0.018, respectively). Increased expression of CD94/NKG2A restricted to tumor-infiltrating CD 8+ T cell subsets may shape the cytotoxic responses, which indicate a possible role of tumor escape from host immunity in human EC