Investigation of the Effect of KIR–HLA Pairs on Hepatocellular Carcinoma in Hepatitis C Virus Cirrhotic Patients

Natural killer cells are partially mediated through the binding of killer cell immunoglobulin-like receptors (KIR) with human leukocyte antigen (HLA) class I ligands. This investigation examined the risk of hepatocellular carcinoma (HCC) in relation to KIR-HLA pairs in patients with compensated hepatitis C virus (HCV)-associated cirrhosis. A total of 211 Japanese compensated HCV cirrhotic cases were retrospectively enrolled. After KIR, HLA-A, HLA-Bw, and HLA-C typing, associations between HLA, KIR, and KIR-HLA combinations and HCC development were evaluated using the Cox proportional hazards model with the stepwise method. During a median follow-up period of 6.6 years, 69.7% of patients exhibited HCC. The proportions of HLA-Bw4 and the KIR3DL1 + HLA-Bw4 pair were significantly higher in patients with HCC than in those without (78.9% vs. 64.1%; odds ratio (OR)-2.10, 95% confidence interval (CI)-1.10-4.01; p = 0.023 and 76.2% vs. 60.9%, odds ratio-2.05, p = 0.024, respectively). Multivariate analysis revealed the factors of male gender (hazard ratio (HR)-1.56, 95% CI-1.12-2.17; p = 0.009), α-fetoprotein > 5.6 ng/mL (HR-1.56, 95% CI-1.10-2.10; p = 0.011), and KIR3DL1 + HLA-Bw4 (HR-1.69, 95% CI-1.15-2.48; p = 0.007) as independent risk factors for developing HCC. Furthermore, the cumulative incidence of HCC was significantly higher in patients with KIR3DL1 + HLA-Bw4 than in those without (log-rank test; p = 0.013). The above findings suggest KIR3DL1 + HLA-Bw4, in addition to HLA-Bw4, as a novel KIR-HLA pair possibly associated with HCC development in HCV cirrhosis. HCV-associated cirrhotic patients with the risk factors of male gender, α-fetoprotein > 5.6 ng/mL, and KIR3DL1 + HLA-Bw4 may require careful surveillance for HCC onset.