Soluble Donor DNA Concentrations in Recipient Serum Correlate with Pancreas-Kidney Rejection

BACKGROUND: There is no reliable serum marker available to monitor incipient pancreas or islet-cell rejection. We tested the hypothesis that quantification of donor-specific genomic DNA in serum (from tissue damage) can serve as a marker of rejection. METHODS: Using a recently developed panel of HLA-specific quantitative PCR assays (Q-PCR), we tested 158 sera from 42 pancreas-kidney transplant recipients. Temporally related biopsies for 65 sera permitted analysis for correlation of donor DNA concentrations with rejection. RESULTS: Donor DNA concentrations were higher in sera from recipients who had experienced allograft rejection (n = 31) than from those who had not (n = 34). Median concentrations, expressed as the genome-equivalent (gEq) number of donor cells per 10(6) host cells, were 2613 and 59 gEq/10(6), respectively (P = 0.03). CONCLUSION: Q-PCR for donor-specific genetic polymorphisms merits further investigation as a noninvasive approach to monitor pancreas-kidney as well as other types of allograft rejection.