Tacrolimus Withdrawal After Mesenchymal Stromal Cell Therapy Is Associated With Donor-Specific Antibody Formation in Kidney Transplant Recipients

Tacrolimus withdrawal after MSC therapy is associated with an increased rate of dnDSA formation in KTRs. However, no increased risk of rejection or inferior graft function was found, raising the question on the pathogenicity of these DSA, despite the presence of complement fixing IgG subclasses. We found that patients with a high HLA class II eplet mismatch load were less likely to tolerate tacrolimus withdrawal without developing dnDSA, which is in line with previous findings that HLA eplet mismatch load modulates tacrolimus through levels required to prevent dnDSA formation. Further research is warranted to explore HLA molecular mismatch load as a biomarker to guide personalized immunosuppression in transplantation.