B Cell Lymphocyte in Humoral Rejection and Alloimmunisation

Inclusion criteria : * Non stable patients : * Patient older than 18 years old. * Patient which is the recipient of a renal transplant * Patient who develops anti donor antibodies after the transplantation and / or suffering from a histologically-proven antibody mediated rejection. * Patient who has signed an informed consent form * Stable patients : * Patient older than 18 years old. * Patient that is the recipient of a renal transplant for more than one year * Patient who has accepted to participate in the Brest Kidney graft recipient collection * Patient that is not suffering from any rejection, that has a good renal function and a low proteinuria * Patient that has not developed any DSA. Exclusion criteria : \- Patients that has not signed the consent form.