RISK OF REJECTION FOR LUNG RECIPIENTS PREDICTED USING ELISPOT TO DETECT IFN-γ PRODUCING CELLS.

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RISK OF REJECTION FOR LUNG RECIPIENTS PREDICTED USING ELISPOT TO DETECT IFN-γ PRODUCING CELLS.
Karen Mohler , Kay Savik , Angela Burnette , Marshall Hertz , Mark Steele , Scott Palmer , R. Duane Davis and Nancy L. Reinsmoen . Durham NC, Duke University Medical Center, 27710, Pathology and Minneapolis MN, University of Minnesota, Pulmonary Medicine .

Alloreactive T cells are primary mediators of acute rejection (AR) and are also thought to play a role in eventual chronic rejection. The Enzyme-Linked Immunosorbent Spot (ELISpot) assay has been used to measure IFN-g producing memory T cells. High frequencies of these cells correlate with early AR in kidney recipients (recips). Presumably, memory T cells are primed by environmental antigens that cross-react with donor histocompatibility antigens. The aim of our study was to determine if a high frequency of IFN-g producing T cells in pretransplant specimens identified lung recips at high risk for early AR (diagnosed by transbronchial biopsy using ISHLT criteria). The frequency of IFN-g producing cells was determined for 46 lung recips transplanted at our 2 centers. The recip cells were incubated for 18 hrs with CD3 depleted third party cells expressing various HLA-DR antigens. The IFN-g produced by single cells was detected by a secondary enzyme-linked antibody and counted using an automated computer-assisted image analyzer. 12 of the 46 recips had AR grade 2 or higher within six months. Of those 12 recips, 8 had frequencies ≥100 spots/200,000 cells. Of the 28 recips with low frequencies (<100 spots), only 4 had early AR. The ELISpot assay identified 67% of recips with ≥ grade 2 AR within six months, and more significantly, 86% of recips with low IFN-g frequencies had no AR within six months (p = .001). Determination of recipients’ memory T cell frequencies appears to identify the risk level for early immune complications and may allow clinicians to guide the use of appropriate immunosuppressive therapy and targeted interventions aimed at improving long-term graft survival.