Polymorphisms of killer cell immunoglobulin-like receptor gene: possible association with susceptibility to or clearance of hepatitis B virus infection in Chinese Han population

Abstract

Aim: To explore whether killer cell immunoglobulin-like receptors (KIR) gene polymorphisms are associated with susceptibility to persistent hepatitis B virus (HBV) infection or HBV clearance.

Methods: Fifteen known KIR genes were determined in 150 chronic hepatitis B patients, 251 spontaneously recovered controls, and 412 healthy controls by the sequence specific primer polymerase chain reaction (SSP-PCR) method. KIR genotype frequency (gf) differences were tested for significance by two-tailed Fisher exact test or chi(2) test. Multifactorial analysis was also performed by logistic analysis (the SAS system).

Results: Framework genes KIR2DL4, KIR3DL2, KIR3DL3, and KIRZ were present in all individuals. The frequencies of KIR2DS2 and KIR2DS3 were higher in chronic hepatitis B patients, than in both healthy and spontaneously recovered controls. The frequencies of activating KIR2DS1, KIR3DS1, and the inhibitory KIR2DL5 were higher in spontaneously recovered controls than in chronic hepatitis B patients and healthy controls.

Conclusion: KIR polymorphisms may be associated with susceptibility to HBV infection or HBV clearance. It could be suggested that KIR2DS2 and KIR2DS3 were HBV-susceptive genes, which induced a persistent yet weak inflammatory reaction that resulted in continuous injury of live tissues and chronic hepatitis. KIR2DS1, KIR3DS1, and KIR2DL5, on the other hand, may be protective genes that facilitated the clearance of HBV.

Figure 1

Amplification production electrophoresis picture of a chronic hepatitis B patient. The corresponding digits represent: 1,2 – KIR3DL1; 3,4 – KIR3DL2; 5,6 – KIR3DS1; 7,8 – KIR3DL3; 9,10 – KIR2DL5; 11,12 – KIRZ; 13,14 – KIR2DL1; 15,16 – KIR2DL2; 17,18 – KIR2DL3; 19,20 – KIR2DL4; 21,22 – KIR2DS2; 23,24 – KIR2DS3; 25,26 – KIR2DS4; 27 – KIR2DS5; 28,29 – KIR2DS1; M – M-DNA marker. All KIR phenotypes were positive except KIR2DS3 (19,20).

Figure 2

Comparison of killer cell immunoglobulin-like receptors gene frequencies. Closed bars – healthy controls; open bars – chronic hepatitis B group; gray bars – spontaneously recovered controls.