CD26 expression on donor harvest as a risk predictive biomarker for developing Graft-versus-Host Disease post-Allogeneic Hematopoietic Stem Cell Transplantation: A tenyear followup study.

BACKGROUND Allogeneic hematopoietic stem cell transplantation (ASCT) is the preferred treatment option for patients with several hematologic disorders and immunodeficiency syndromes. Graft versus host disease (GVHD) is an immune mediated post-transplant complication which has a major impact on long term transplant outcomes. OBJECTIVE Current efforts are focused on identification of new markers that serve as potential predictors of GVHD and other post-transplant clinical outcomes. METHODS This study includes donor harvests collected from twenty-three allogeneic donors during period 2008-2009 and respective transplant recipients followed for clinical outcomes till March 2019. Percent CD26+ and CD34+ cells in donor harvest were analyzed using flow cytometry. Percent expression and infused dose of CD26+ and CD34+ cells were evaluated for association with various clinical outcomes. RESULTS Total 23 healthy donors 28 years (13 males), and transplant recipients with median age 24 years (17 males) formed the study cohort. The diagnosis included malignant (n= 13) and non-malignant (n= 10) disorders. Median CD34brCD45lo HSC expression was 057% (IQR 024-103) while median CD26 expression was 1964% (IQR 896-3356) of all nucleated cells. CD26 expression was associated with donor age (P= 0.37). CD26 percent expression correlated with WBC engraftment (P= 0.015) and with acute GVHD (P= 0.023) whereas infused CD26 cell dose correlated with WBC engraftment (P= 0.004) and risk of CMV reactivation (P= 0.020). There was no statistically significant correlation of either CD26 expression or cell dose with chronic GVHD, EFS or OS.