HLA-KIRs interactions in modulating natural killer cell responses against viral hepatitis: a concise review

Killer immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) molecules play an essential role in regulating immune responses against hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. HLA-KIRs interactions are crucial for activating and inhibiting the natural killer (NK) cell system through a modulation that shapes these cells to kill infected cells and release cytokines. Regulation underlies the anti-viral function of the NK cell and profoundly affects viral clearance, immune evasion, and the course of disease. Activating KIRs such as KIR2DS1 and KIR3DS1 cooperate with specific HLA ligands in boosting NK cell responses against the virus, thereby facilitating viral elimination. In contrast, inhibitory KIRs like KIR2DL1 and KIR3DL1 bind to HLA-C2 and HLA-Bw4, respectively, imposing a dampening influence on NK cell activation, which allows the virus to persist and progress to chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). These variations in KIRs and HLA genes will also affect an individual’s susceptibility to infections, disease severity, and their response to antiviral therapies. Observation of the role of KIRs and their interaction with HLA at the immunogenetic level provides valuable insight into host-virus dynamics and opens up many therapeutic avenues. Targeting immunotherapies toward NK cell pathways and developing personalized medicine may boost antiviral immune responses and improve treatment outcomes in chronic viral hepatitis patients. This review recognizes HLA-KIRs interactions as potent biomarkers for disease progression and determining treatment strategies.