Alloreactive Memory B Lymphocytes and Anti-HLA Sensitization

Inclusion Criteria: * Age ≥ 18 years * Rouen University Hospital patient monitored in the Nephrology and Kidney Transplantation Department, registered on the national kidney transplant waiting list * Carrier of HLA antibodies, including at least anti-HLA2, identified during the last screening * Notion of classic immune-promoting events including at least one previous transplant or pregnancy, or absence of a known immune-promoting event (naïve patient group) * Incompatible graft rate (IGR) * IGR ≥ 85% (hyperimmunized patient group with anti-HLA polyreactivity) or * IGR between 50% and 85% (immunized patient group with a more restricted repertoire of HLA reactivities) or * IGR \< 50% (naïve patient group with no known history of immune-promoting events) * Person who has read and understood the information letter and does not object Not participating in the study * Affiliation to a social security scheme Exclusion Criteria: * Patients who have received rituximab in the previous year (B-cell depleting therapy) * Patients undergoing an HLA desensitization protocol using plasmapheresis and/or rituximab * Patients with an active infection * Persons deprived of their liberty by an administrative or judicial decision or persons placed under judicial protection/guardianship or curatorship