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.