Predictive Role of Circulating Immune Cell Subtypes Early after Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Acute Leukemia

ABSTRACT

BACKGROUND AND OBJECTIVES: Cells of innate immunity normally recover in the first weeks to months after allogenenic hematopoietic stem cell transplantation (allo-HSCT). Their relevance in terms of graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effect is largely unknown. The predictive role of early recovery in the immune cells on acute GVHD and GVL effect after allo-HSCT was investigated in patients with acute leukemia who achieved the first complete remission. METHODS: Peripheral blood samples were taken at the median of 14 days (range, 12~29 days) after allo-HSCT. A cohort including 119 samples and characteristics of patients were analyzed. Immune cell populations were identified by flow cytometry. RESULTS: The median age was 49.0 years (range, 21~69) at transplantation. Univariate analysis showed that age less than 40 years old, lower frequencies of CD8+ T cells, invariant natural killer T (iNKT) cells, monocytic myeloid derived suppressor cells (M-MDSCs) and higher frequency of immature MDSCs were associated with occurrence of grade III–IV acute GVHD. Multivariate analyses showed that iNKT cells (hazard ratio (HR), 0.453, 95% CI, 0.091~0.844, p=0.024) and M-MDSCs (HR, 0.271, 95% CI, 0.078~0.937, p=0.039) were independent factors. Combination of higher frequencies of both cell subsets was associated with lower incidence of grade III–IV acute GVHD, whereas patients with lower frequency of iNKT cells and higher frequency of M-MDSCs showed significant higher probability of relapse. CONCLUSIONS: iNKT cells and M-MDSCs could be relevant cell biomarkers for predicting acute GVHD and/or relapse in acute leukemia patients treated with allo-HSCT.