DONOR–SPECIFIC SINGLE CELL DETECTION OF IFN–[g] PRODUCTION IDENTIFIES RENAL RECIPIENTS AT HIGH RISK FOR EARLY ACUTE REJECTION

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TITLE: DONOR–SPECIFIC SINGLE CELL DETECTION OF IFN–[g] PRODUCTION IDENTIFIES RENAL RECIPIENTS AT HIGH RISK FOR EARLY ACUTE REJECTION

Karen Mohler,¹ Angela Burnette,¹ Arthur Matas,² Nancy Reinsmoen.¹

¹Pathology, Duke University Medical Center, Durham, NC, USA; ²Surgery, University of Minnesota, Minneapolis, MN, USA

Alloreactive T cells are primary mediators of biopsy–proven acute rejection (AR) and are thought to play a role in subclinical AR and in biopsy–proven chronic rejection (CR). Measuring the frequency of the donor–specific T cells may reflect the strength of the in vivo immune response. The aim of our study was to determine if the frequency of donor specific IFN–[g] producing T cells identified recipients at high risk for AR and subsequent CR. We studied 15 renal recipients including 5 with early (<3 mo) AR, 2 with late AR and 8 with no episodes of biopsy–proven AR. Samples were obtained pretransplant and at various times posttransplant (6 wks – 3 yr). The frequency of IFN–[g] producing cells was determined by the Enzyme–linked Immunosorbent Spot Assay (ELISpot). Recipient cells were incubated for 18 hours with CD3 depleted donor cells or third party cells. The IFN–[g] produced by single cells was detected by a secondary enzyme–linked antibody and counted using an automated computer–assisted image analyzer. The pretransplant frequency of donor specific IFN–g producing cells was higher in recipients who experienced EAR (mean = 67, range = 7–211 IFN–[g] spots/200,000 cells or 45–65% of third party control frequency) than in 9 recipients with no AR or late AR (mean = 30, range = 8–63 IFN–[g] spots/200,000 cells or 12–43% of third party frequency). One recipient tested at the time of AR showed a 146% increase of current to pretransplant donor–specific IFN–[g] frequencies. Identification of recipients with preexisting or increasing donor specific frequencies appears to identify those recipients at high risk for AR and may allow clinicians to guide the use of appropriate immunosuppressive therapy and targeted interventions aimed at improving long–term graft survival.