Comparison of Transcriptional and Blood Cell‐Phenotypic Markers Between Operationally Tolerant Liver and Kidney Recipients

A proportion of transplant recipients can spontaneously accept their grafts in the absence of immunosuppression (operational tolerance). Previous studies identified blood transcriptional and cell‐phenotypic markers characteristic of either liver or kidney tolerant recipients. However, the small number of patients analyzed and the use of different transcriptional platforms hampered data interpretation. In this study we directly compared samples from kidney and liver tolerant recipients in order to identify potential similarities in immune‐related parameters. Liver and kidney tolerant recipients differed in blood expression and B‐cell immunophenotypic patterns and no significant overlaps were detectable between them. Whereas some recipients coincided in specific NK‐related transcripts, this observation was not reproducible in all cohorts analyzed. Our results reveal that certain immune features, but not others, are consistently present across all cohorts of operationally tolerant recipients. This provides a set of reproducible biomarkers that should be explored in future large‐scale immunomonitoring trials. Comparison of blood transcriptional profiles from kidney and liver operationally tolerant recipients reveals several highly reproducible immune features but very little overlap between the two clinical settings.