Presented at:
7th Trends in Immunosuppression
Berlin, Germany, February, 2006
Fingerprinting tolerance in Renal Transplantation
Sagoo P, Hernandez-Fuentes M, Jimenez-Vera E, Rovis F, Hilton R, Warrens A, Lechler RI
King's College London, UK; Guy's Hospital, London, UK. Imperial College, London, UK
AIM: Induction of tolerance is a desired long-term outcome for renal transplant patients. This ongoing study scrutinizes the cellular basis of tolerance in terms of specific anti-donor responses and the regulatory activity of CD4+CD25+ Tregs in 4 specific groups of renal transplant recipients (1) Stable renal function on a CNI based immunosuppressive therapy, (2) Stable renal function on a non-CNI based therapy, (3) Patients undergoing chronic rejection and (4) drug-free Tolerant recipients.
METHODS: Quantitative assessments of donor-specific responses are made by IFNgamma ELISpot. Responder cell frequencies generated by the indirect pathway are made by stimulating recipient PBMCs with solubilised donor membrane proteins. Frequencies of direct pathway donor-reactive CD8 and CD4 T cells are studied by stimulation with donor-derived APCs. Direct pathway T cell responder frequencies are also estimated by CFSE analysis. Depletion of CD4+CD25+ cells from responder populations in these assays further uncovers Treg-mediated regulation of anti-donor responses.
RESULTS: Interim data analysis shows that using these assays donor-specific hypo- and hyper-responsiveness is detected, along with donor-specific Treg activity. By performing these assays in parallel on each patient group, immunological differences can be detected which may govern the tolerant state. We expect that with more patients analysed by the study end-point, a clinically important answer should be obtained.
CONCULSIONS: Combined with data from molecular and genetic studies (in vivo DTH, Micro-array, TCR-Landscaping) on these same patients, this data should significantly further our understanding of regulatory mechanisms during chronic rejection and tolerance and provide an immunological ‘fingerprint’ of the tolerant state.