Abstract: FR-OR072
Regulatory B Cell Phenotypes in Kidney Transplant Recipients and Their Association with Graft Function
Session Information
- Transplantation: Basic Science Innovations and Advances
November 07, 2025 | Location: Room 370A, Convention Center
Abstract Time: 05:50 PM - 06:00 PM
Category: Transplantation
- 2101 Transplantation: Basic
Authors
- Aly, Mostafa Gaafar, Transplantation Immunology, Institute of Immunology, University Hospital Heidelberg,, Heidelberg, Germany
- Ibrahim, Eman Hosny, Transplantation Immunology, Institute of Immunology, University Hospital Heidelberg,, Heidelberg, Germany
- Morath, Christian, Department of Nephrology, University Hospital Heidelberg, Heidelberg, Germany
- Daniel, Volker Rüdiger Maria, Transplantation Immunology, Institute of Immunology, University Hospital Heidelberg,, Heidelberg, Germany
Background
Regulatory B cells (Bregs) are CD19+ lymphocytes with diverse immunosuppressive roles, yet no single definitive surface marker distinguishes them, and their impact on alloimmunity after kidney transplantation remains unclear.
Methods
Ninety-four stable renal transplant recipients were included. Breg subsets—CD19+IL-10+, CD19+CD24hiCD27+, CD19+CD24hiCD38hi, CD19+CD5+, CD19+CD1d+, and CD19+CD25+CD73-CD71+—were quantified by flow cytometry. Associations between Breg counts and key clinical parameters were assessed in the overall cohort and stratified into early (≤1 year, n=47) and late (>1 year, n=47) post-transplant periods.
Results
Early recipients exhibited significantly higher counts of IL-10+, CD24hiCD38hi and CD1d+ Bregs compared with late recipients (p=0.002, 0.001, 0.021). In the full cohort, CD24hiCD38hi Bregs inversely correlated with rejection (r=–0.252, p=0.025) and, alongside CD1d+Bregs, with CRP (r=–0.471, p<0.001; r=–0.243, p=0.030). CD24hiCD27+ and CD25+CD73-CD71+Bregs positively associated with GFR (r=0.287, p=0.010; r=0.376, p<0.001).
Ciclosporin troughs and steroid dose correlated with higher IL-10+, CD24hiCD27+ and CD24hiCD38hi Bregs (ciclosporin: r=0.400, 0.401, 0.355; p=0.017, 0.017, 0.036; steroids: r=0.285, 0.319, 0.416; p=0.011, 0.004, <0.001), and steroids also correlated with CD5+Bregs (r=0.252, p=0.027). Tacrolimus troughs correlated with IL-10+Bregs (r=0.361, p=0.031).
Among early recipients, CD5+, CD24hiCD38hi and IL-10+Bregs inversely correlated with rejection (r=–0.351, –0.314, –0.417; p=0.024, 0.043, 0.007), while CD24hiCD27+Bregs inversely correlated with DGF (r=–0.449, p=0.003) and, alongside CD24hiCD38hi, with serum creatinine (r=–0.337, –0.333; p=0.027, 0.029). In late recipients, CD24hiCD27+ and CD25+CD73-CD71+Bregs associated with better GFR (r=0.474, p=0.001; r=0.343, p=0.038) and, with IL-10+Bregs, with reduced de novo DSA (r=–0.418, –0.349, –0.490; p=0.019, 0.025, 0.005).
Conclusion
Breg counts fall in the late posttransplant phase but are preserved under standard immunosuppression. Among all subsets, CD24hiCD38hi, CD24hiCD27+ and IL-10+Bregs show the strongest, consistent links to lower rejection rates, reduced inflammation and better graft function—supporting their use as dynamic biomarkers and targets for personalized immunomodulation to improve long-term transplant outcomes.