In adult kidney transplant recipients a therapy-responder and non-responder phenotype by antibody mediated rejection will be precisely defined according to clinical and histological characteristics such as creatinine, proteinuria and Banff-classification. Twenty-five patients will be selected each in the therapy-responder and non-responder group. Their stored Formalin Fixed Paraffin Embedded (FFPE) biopsies will be (re)-classified according to the most recent Banff classification. Using Nanostring Technology the gene transcription of therapy-responders versus non-responders will be analyzed and compared to serological and clinical parameters.

Inclusion Criteria:

• Kidney transplant patients at the University Hospital of Zurich between 01.01.2008 - 31.12.2016 with histologically suspected or confirmed ABMR
• Written consent for further use of data for research purposes

Exclusion Criteria:

• Age at transplantation < 18 years
• Combined organ transplantation (incl. Kidney-Pancreas, Kidney-Liver, Kidney-Heart)
• Incomplete laboratory and/or clinical data
• Recurrence of the initial disease
• Insufficient Biopsy Material for NanoString Analysis
• Documented refusal of further data analysis for research purpose

All ABMR cases in patients who received a kidney transplant between 01.01.2008 - 31.12.2016 will be pre-screened. As an approximate number of 90 kidney transplantations are performed per year at the University Hospital of Zürich, a total of approximately 810 patients will be available for analysis. Yet, according to the inclusion/exclusion criteria we estimate roughly 50 patients to be finally recruited for analysis. Since we estimate a consent rate of about 50%, we will roughly contact 100 patients. A subset of 25 responders and 25 non-responders according to the clinical course will be identified for further analysis