OR12 Monitoring CD8+ donor lymphocyte chimerism is a critical indicator for diagnosing and treating acute graft vs. host disease following liver transplantation

Aim Mortality of Acute Graft vs. Host Diseases (aGvHD) after Liver Transplantation (LT) can be as high as 70–100%, due to delays in diagnosis and severity of complications. Based on a large LT cohort with long term follow up, we investigated the role of donor chimerism (D%) in supporting expeditious aGvHD diagnosis and monitoring disease control. Methods 145 of 1478 recipients with LT during 9/2007-12/2017 were clinically suspected to have aGvHD and tested for D% with peripheral blood (PB), CD3 + (T), CD8 + T, NK, and B lymphocytes by short tandem repeat (sensitivity 5%). D% at initial testing and peak stage, POD of aGvHD resolution, and aGvHD related mortality were retrospectively analyzed. Clinical suspicions with CD8 + T D% u003e25% were initially treated with methylprednisolone and/or reduced immunosuppression. Thymoglobulin was added to cases with no improvement after initial therapy. Results The D% in PB was uninformative. The highest D% was seen in CD8 + T cells followed by T cells and NK cells. Of 145 recipients with D% test, 27 had D% u003e 5, these patients were then graded into clinical severity as C0-3. Nine patients in C0 had no clinical evidence of aGvHD, whereas 18 patients were graded as C1-3. C2 and C3 (n = 9) had average CD8 + T D% ⩾ 75±23% at initial testing and ⩾ 86±24% at peak D% stages, which were significantly higher than that of C1 (n = 9) with p  Conclusions The D% of CD8 + T cell is a sensitive and correlative indicator for timely diagnosis and effective monitoring of aGvHD after LT. High D% of CD8 + T from initial testing and peak phase was associated with aGvHD related mortality or prolonged resolution of this disease. Early detection of D% of CD8 + T before the donor immune system fully engrafted is critical for recovering from the damage of aGvHD following LT.