Gamma delta T cell reconstitution in Acute Lymphoblastic Leukemia patients post allogeneic HSCT predicts clinical outcome and overall survival.

Predicting the transplant outcome of Acute Lymphoblastic Leukemia patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a challenge. It is necessary to have prognostic biomarkers that can be monitored in these patients. In the present single center, long term follow-up study, immune cell composition or the immunophenotype of Acute Lymphoblastic Leukemia patients (n = 14) was analyzed at various intervals following allogeneic HSCT and correlated with clinical outcomes. Long-term survivors post-HSCT showed distinct immune cell profiles compared to non-survivors. Long term survivors exhibited higher expression of Vδ2+CD69+ (p = 0.0126), and Vδ1+CD16b+ T cells (p = 0.0485) at baseline, compared to non-survivors. The analysis of donor immune cell composition showed difference at baseline, donors with higher levels of NKT+ cells and lower Vδ1+perforin+ T cells led to longer survival of respective recipients. Earlier WBC engraftment and incidence of chronic GVHD were other independent clinical factors associated with higher overall survival post- allogeneic HSCT. Furthermore, donors with higher baseline percentages of γδ T cells, CD19+ B cells, CD4 T cells, Vδ2 Naïve, Vδ2 TemRA, CD3+CD25+, and Vδ2+CD25+; and low Effector Memory CD3+ and Vδ1+ T cells were associated with fewer Cytomegalovirus (CMV) reactivation in their recipients. The present study underscores the importance of compositional analysis of immune cells in both recipients and donors as a discerning predictive tool for anticipating long-term clinical outcomes following allogeneic HSCT and highlights the need for future validation in larger cohorts.