Cell-free DNA as a noninvasive acute rejection marker in renal transplantation.
BACKGROUND
Acute rejection (AR) is a key conditioning factor for long-term graft function and survival in renal transplantation patients. The standard care with creatinine measurements and biopsy upon allograft dysfunction implies that AR is usually detected at advanced stages. Rapid noninvasive biomarkers of rejection are needed to improve the management of these patients. We assessed whether total cell-free DNA (tCF-DNA) and donor-derived cell-free DNA (ddCF-DNA) were useful markers for this purpose, both in plasma and in urine.


METHODS
Plasma and urine samples from 100 renal transplant recipients were obtained during the first 3 months after transplantation. tCF-DNA and ddCF-DNA were analyzed by quantitative PCR for the HBB (hemoglobin, beta) and the TSPY1 (testis specific protein, Y-linked 1) genes, respectively. We observed 19 episodes of AR, as well as other complications, such as acute tubular necrosis, nephrotoxicity, and infections.


RESULTS
Plasma tCF-DNA concentrations increased markedly during AR episodes, often before clinical diagnosis, and returned to reference values after antirejection treatment. A cutoff plasma tCF-DNA concentration of 12 000 genome equivalents/mL correctly classified AR and non-AR episodes in 86% of posttransplantation complications (diagnostic sensitivity, 89%; specificity, 85%). Although similar increases were observed during severe posttransplantation infections, use of the combination of plasma tCF-DNA and procalcitonin (PCT), a specific marker of sepsis, significantly improved the diagnostic specificity (to 98%; 95% CI, 92%-100%), with 97% of the episodes being correctly classified. Use of transrenal DNA and ddCF-DNA concentrations did not add relevant information.


CONCLUSIONS
Given that renal biopsy is the gold standard for detecting AR, analysis of both plasma tCF-DNA and PCT could permit a more selective use of this invasive procedure.
García Moreira
Vanessa
V
Biochemistry Laboratory and Nephrology and Bone Metabolism Unit, Hospital Universitario Central de Asturias, Asturias, Spain.
Prieto García
Belen
B
Baltar Martín
Jose M
JM
Ortega Suárez
Francisco
F
Alvarez
Francisco V
FV
D000293:Adolescent; D000328:Adult; D000368:Aged; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide; D018797:Cell Cycle Proteins / Q000235:genetics; D004247:DNA / Q000097:blood / Q000652:urine; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis*; D006801:Humans; D016030:Kidney Transplantation / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011498:Protein Precursors; D014019:Tissue Donors; D055815:Young Adult; D055544:beta-Globins / Q000235:genetics
C000606589:CALCA protein, human; D018797:Cell Cycle Proteins; D011498:Protein Precursors; C497749:TSPY1 protein, human; D055544:beta-Globins; D002116:Calcitonin; D004247:DNA; D015740:Calcitonin Gene-Related Peptide