A Study On The Association Of KIR And HLA Genetic Diversity With Acute Rejection In Liver Transplantation

BackgroundKiller cell immunoglobulin-like receptors(KIRs)regulate NK cell activities through interaction with class I human leukocyte antigen(HLA),which play an important role in the immune response of transplantation.The KIR genes cluster on chromosome 19q13.4 consists of 14 functional loci and two pseudogenes.The structure of KIR genes is extremely complicated.KIR genes not only have allelic polymorphism,but also exhibit extra diversity of haplotype content.Since the frequencies of KIR and HLA alleles differ with ethnicities,the varied and inconsistent outcomes were seen in previous retrospective studies while investigating the impact of KIR-HLA diversity on liver acute rejection.The present study focused on the association of KIR and HLA genetic diversity with acute rejection(AR)after liver transplantation in Southern Chinese Han population for the first time.SubjectPeripheral blood samples were collected from 143 recipients and 78 donors with informed consent at a single liver transplantation center during the period of March 2015 to June 2017,all the donors and recipients are of the Han ethnicity from southern China.The follow-up time for each recipient after transplantation is more than 6 months with a mean value of 7.4 months(Ranged from 6?27 months).Thirty three recipients with confirmed AR and 110 recipients without acute rejection were observed based on Banff Schema for liver allograft rejection.MethodsDNA samples of all recipients were subjected to KIR-SSP genotyping at low-resolution to identify the presence or absence of KIR genes,firstly.Samples with demonstrated KIR genes were then genotyped by sequencing-based typing(PCR-SBT)at high-resolution to obtain the exact allelic genotype.HLA-A,-B,-C genotyping by reverse sequence specific oligonucleotide probe-PCR(PCR-rSSO)was performed for all the recipients and donors.By direct counting the number of identified HLA and KIR alleles present in the study samples,the significant difference of HLA-KIR polymorphic factor was subjected to x2 or Fisher test using the IBM SPSS Statistics 20 software.Results(1)The mean age and gender of recipients showed no significant difference(P>0.05)while compared the acute rejection(AR)group with the non-acute rejection(NAR)group,respectively.(2)The impact of low-resolution KIR diversity of recipients on AR:The observed frequencies for each functional KIR gene,KIR haplotype group and KIR profile showed no significant difference(P>0.05)while compared the AR group with NAR group.(3)The impact of high-resolution KIR allelic diversity of recipients on AR:each liver transplantation recipient was subjected to Sanger sequencing by PCR-SBT for all the 14 functional KIR genes,a total of 21338 sequences were obtained and 74 KIR alleles were identified in the present paper.However,the observed frequency of each KIR allele showed no significant difference(P>0.05)while compared the AR group with the NAR group.(4)The influence of HLA ligand on AR:Compared with NAR group,a benefit for significant decreased risk of AR was observed for recipients who received graft from a donor with HLA-C1C1 genotype(AR vs NAR group:47.1%vs 75.4%,P=0.03).However,donors having HLA-C1C2 genotype exhibited significant increased risk of AR(AR vs NAR:52.9%vs 19.7%,P=0.01).(5)Analyzing the frequencies of each "KIR gene of recipient and its cognate HLA ligand from liver donor",we found that 2DS4 positive recipient and donor having HLA-C2 exhibited a significant increased risk of AR(AR vs NAR group:50.0%vs 21.7%;P=0.03).Moreover,"2DS4*00101 positive recipient and donor having HLA-C2" presented a significant increased risk of AR(AR vs NAR group:43.8%vs 15.0%,P=0.03).Conclusions and significanceFor the first time,the present paper has demonstrated that liver donor with HLA-C1C1 genotype can confer a protective effect as a significant decreased risk of AR,whereas donors having HLA-C1C2,"2DS4 positive recipient and donor having HLA-C2" and "2DS4*00101 allele positive recipient and donor having HLA-C2" can confer AR risk in liver transplantation.Our results implied that immune surveillance and immunosuppression should be emphasized for recipient receiving a graft from a donor with HLA-C1C2 genotype in case of acute rejection.These findings can provide valuable information and clues for elucidating the pathogenesis of AR,making personal immunosuppressive regimen,predicting and prevention of AR after liver transplantation in Southern Chinese Han population.