Highly sensitised individuals present a distinct Treg signature compared to unsensitised individuals on haemodialysis

Highly sensitised (HS) patients represent up to 30% of patients on the kidney transplant waiting list. When they are transplanted, they have a high risk of acute/chronic rejection and long-term allograft loss. Regulatory T cells (Tregs) (CD4 CD25 CD127 ) are cells involved in the suppression of immune alloresponses. A particular subset, called T follicular regulatory T cells (Tfr, CXCR5 Bcl-6 ), is involved in regulating interactions between T effectors and B cells within the germinal centre and can be found in peripheral blood. Therefore, we wanted to identify specific subsets of Tregs in the peripheral blood of HS individuals. We recruited prospectively healthy volunteers (HV) ( = 9), non-sensitised patients on haemodialysis (HD) ( = 9) and HS individuals, all of whom were on haemodialysis ( = 15). We compared the Treg phenotypes of HV, HD and HS. HS patients had more CD161 Tregs ( = 0.02) and more CD45RA CCR7 T effectors (Teffs) ( = 0.04, memory Teffs able to home to the germinal centre) compared to HVs. HS patients had more Bcl-6 Tregs (