Table 1.
Biomarkers of tolerance in liver transplantation
| Biomarker | Description | Study before or during IS withdrawal | Ref. |
| Dendritic cells | |||
| pCD/mCD ratio | Tolerant patients have elevated pDC/mDC ratio. No differences between tolerant patients vs healthy controls | No | [134,150] |
| mDCs/pCD ratio | Elevated mDC/pCD associated with late rejection | No | [151] |
| PD-L1/CD86 ratio | Elevated PD-L1/CD86 expression on DCs in tolerant patients | No | [152] |
| DC HLA-G expression | Elevated on mDC | No | [153] |
| T cells | |||
| Regulatory T cells | Increase of peripheral CD4+CD25high cells and RNA FoxP3 over time during weaning | Yes | [40,43,44,133] |
| Increase in T regs in liver biopsy of tolerant patients | |||
| Natural killer | Increase in Tolerant patients | Yes | [154] |
| Soluble factors | |||
| Serum HLA-G | Normal or elevated serum HLA-G levels associated to normal liver | No | [155-157] |
| Anti-donor antibodies | Absent in tolerant patients | No | [150] |
| Cell proliferation | |||
| Phytohemagglutinin SI | SI < 20 and > 10 yr since LT 100% tolerance | Yes | [158] |
| Genetic profile | |||
| Cytokine gene polymorphism | Low TNF-alpha and high/intermediate IL-10 production in OT | No | [159] |
| Gene transcripts | Enriched from NK, CD4+CD25+ FoxP3+, γδTCR+ and δ1TCR+ | No | [42,43,160] |
| Genes related to iron homeostasis in liver graft | Enriched in tolerant patients (CDHR2, MIF, PEBP1, SOCS1, TRF) | Yes | [140] |
DC: Dendritic cell; mDC: Monocytoid dendritic cell; LT: Liver transplantation; pDC: plasmacytoid dendritic cell; SI: Stimulation index.