Introduction: De novo Donor Specific Antibodies (dnDSA) are associated with antibody-mediated rejection leading to renal transplant failure. However, many transplant patients are stable with no signs of graft dysfunction at the time of dnDSA detection in a routine test.
Materials and Methods: In a routine test including 110 renal transplant patients, at least 6 months after transplantation, dnDSA were detected, using Single Antigen Bead Luminex assay, in 26 (15 males) of them. We prospectively studied these dnDSA positive patients for 3 years. Proteinuria and eGFR were evaluated along with dnDSA monitoring, at least annually.
Results and Discussion: Graft loss associated with dnDSA occurred in 8 (31%) patients, 14±11 months after the initial detection of dnDSA. These patients had more frequently multiple dnDSA (p=0.004) and remarkable proteinuria, more than 1g daily (p<0.001). The remaining 18 patients were followed for 38±15 months and considered stable as there was no deterioration regarding eGFR and proteinuria. In 7(39%) of these patients dnDSA waned and were not detected anymore at follow up. Antibodies against HLA class II had a significant (p<0.001) greater Mean Fluorescence Intensity (MFI) (11109±6414) compared to those against HLA class I (2603±1098) and in regression analysis they were predictive of dnDSA insistence (p=0.043, OR: 0.18, 95%CI: 0.04-0.94). Despite fluctuations during follow up there was no significant change in MFI for those who retained the dnDSA.
Conclusion: The presence of dnDSA is transient in a considerable proportion of stable renal transplant patients, especially in those with antibodies against HLA class I and a low MFI. Multiple dnDSA and significant proteinuria are correlated with an adverse prognosis for graft survival.