Determination of IL28B polymorphisms in liver biopsies obtained after liver transplantation

Recipient and donor IL28B polymorphisms seem to play an important role in the response to hepatitis C treatment after liver transplantation (LT). Since donor peripheral blood mononuclear cells (PBMC) are not always available, the aim of our study was to assess whether follow-up biopsies obtained after LT could be used to determine donor IL28B genotype.

Genotyping of IL28B rs12979860 was performed by TaqMan real-time PCR and direct sequencing in 56 HCV-infected LT recipients and their donors. Liver biopsies were obtained at the moment of LT (reperfusion) and at any time when clinically indicated (follow-up). Direct sequencing always confirmed the real-time PCR results.

Genotyping of donor IL28B rs12979860 polymorphisms showed a 100% match both in PBMC and reperfusion biopsies. The frequency of IL28B rs12979860 polymorphisms differed significantly between donors and follow-up biopsies (p=0.024). We found an enrichment of the IL28B rs12979860 CT genotype (72%) in follow-up biopsies compared to donor samples (46%). Recipient alleles were clearly detected in 14 heterozygous follow-up samples: 10 CT/CC, 1 CT/TT, and 3 TT/CC (recipient/donor), thus reflecting a mixture of both donor and recipient genotypes.

Our results support that follow-up liver biopsies from LT recipients are not suitable for determining donor IL28B rs12979860 genotype by TaqMan real-time PCR or direct sequencing and that PBMC or reperfusion biopsies should be used instead. Thus, it is very important to obtain adequate samples in order to accurately determine the relative contributions of both donor and recipient.