Expression of Inhibitory Receptors in Natural Killer (CD3−CD56+) Cells and CD3+CD56+ Cells in the Peripheral Blood Lymphocytes and Tumor Infiltrating Lymphocytes in Patients with Primary Hepatocellular Carcinoma

The cytolytic responses of NK (CD3−CD56+) and CD3+CD56+ cells are inhibited by the engagement of the killer inhibitory receptors (p58.1, p58.2, and CD94) with respective ligands on the target cell. The expression of these receptors in peripheral blood lymphocytes (PBLs) (n = 18) and tumor infiltrating lymphocytes (TILs) (n = 7) was examined in patients with primary hepatocellular carcinoma (HCC). There were no differences in the expression of the three inhibitory receptors by both NK and CD3+CD56+ PBLs in patients with HCC compared to that of control NK and CD3+CD56+ PBLs, respectively (all P = NS). However, the expression of p58.1 by NK TILs and by CD3+CD56+ TILs in patients with HCC was significantly decreased compared to that of hepatic lymphocytes of the control subjects (8.9% vs 37.85%, P = 0.047; 4.1% vs 25.2%, P = 0.049, respectively). The expression of p58.2 by CD3+CD56+ TILs and CD94 by NK TILs was also decreased compared to that of hepatic lymphocytes of the control subjects (16.9% vs 73.1%, P = 0.047; 21% vs 49.95%, P = 0.037, respectively). These changes were limited to hepatic TILs, and this observation may reflect an adaptive anti-tumor phenomenon occurring in the microenvironment of HCC.