| [Objective] To investigate whether the inheritance of KIR gene polymorphisms could serve as a candidate for the susceptibility to persistent HBV infection.[ Methods ] A total of 75 patients (54 men, 21 women), visited in the Shandong Provincial Hospital between January and August in 2004, who continued to be positive for HBsAg for more than 6 months and did not have any other types of liver disease such as chronic hepatitis C, alcoholic liver disease, autoimmune hepatitis, or primary biliary cirrhosis underwent analysis of the KIRs gene polymorphisms. They were measured of serum ALT and HBV markers such as HBsAg, HBeAg, anti-HBe and anti-HBc using commercially available radioimmunoassay kits and with ultrasonography of the liver. In addition, 324 random healthy donors (212 men and 112 women) were studied as a control group. All 75 persistent HBV-infected cases and 324 randomly healthy controls enrolled to detect the KIR genotype for fifteen KIR genesusing polymerase chain reaction with specific sequence primers (PCR-SSP) analysis. Genomic DNA sample was extracted from 5ml EDTA anticoagulanted peripheral blood with a standard salting-out propedure. The PCR products together with approximately 3μL MBI 100bp DNA ladder served as the molecular weight marker were electrophoresed on 1.5% agarose gels with bromophenol blue. After electrophoresed, the agarose gel was scanned and imaged using an Alphaimager ? 2200 instrument (Alpha Innotech Corporation) and each sample was genotyped. [ Results ] In this study, we typed 15 KIR genes in 75 Chinese cases and 324 healthy controls. All of the KIR genes tested were present in both patients and controls. Generally, three framework genes (2DL4, 3DL2 and 3DL3) and 2DL3, KIRZ were detected in almost all the CHB cases and controls. But in CHB, KIR2DL1 and KIR3DL1 were all detected, although they were absent in some controls (an approximately 0.93% loss for KIR2DL1 and 1.23% loss for KIR3DL1, which were not significant at the 5% level). In the respective comparison of phenotypic frequencies (presence or absence) of KIR genes between CHB patients and healthy control subjects revealed significantly different frequencies of KIR 2DL5 and 2DS2 (KIR2DL5, 51 of 75 (68%) in cases vs 173 of 324 (53.4%) in controls,p=0.0216; KIR2DS2, 32 of 75 (42.67%) in cases vs 89 of 324 (27.47%) in controls, p=0.0099). Furthermore, individuals positive for activating KIR2DS1, KIR2DS3 and KIR2DS5 were more frequently patients than control subjects respectively, these differences did not reach statistical significance, possibly because of the small sample size. No significant differences were detectable between patients and control subjects for activating KIR2DS4, KIR3DS1, and inhibitory KIR2DL2. Individuals from either cohort possessed up to six activating KIR genes. Individuals who possessed one or two activating KIR genes were more frequently control subjects than patients. In contrast, individuals with three or more activating KIR genes were more frequently patients than control subjects (64% vs.50.62%, respectively, p<0.05). And through calculate the number of KIR genes possessed each in patients and controls, we found that the arithmetic mean of activating KIR genes possessed in patients is significantly higherthan that in controls (3.16 vs. 2.72,/?<0.05).[Conclusions] The genetic variation at the KIR locus influences the susceptibility to persistent HBV infection in a Chinese population. A gene dosage effect of the number of activating KIR genes may also tend toward the CHB.The function of these two genes KIR2DS2. KIR2DL5 should be investigated deeply.
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