These indicators may identify patients at increased risk for post-HCT failure and guide therapeutic interventions.įinancial disclosure: This work was supported in part by National Institutes of Health (NIH) grant P30 CA77598 using the Translational Therapy Laboratory Shared Resource of the Masonic Cancer Center, University of Minnesota. Recovery of AMC and classic monocytes were prognostic for survival, relapse, and TRM. In summary, hematopoietic cell source is associated with monocyte subpopulation recovery, with the early robust recovery in UCB recipients. Intermediate and nonclassic monocyte recovery were not associated with outcomes. TRM was also reduced when classic (P =.02)monocyte count exceeded optimal cutpoints. Relapse was reduced for those with AMC (P <.01)and classic (P =.05)monocyte counts above optimal cutpoints. OS and DFS were superior when AMC and classic monocyte recovery were above optimal cutpoints (all P <.03). These were used to calculate hazard ratios for OS, disease-free survival (DFS), relapse, transplant-related mortality (TRM), and acute and chronic graft-versus-host disease. Using 2-fold cross-validation, optimal cutpoints were calculated for day 28 AMC and monocyte subpopulations based on OS. Significant differences in absolute monocyte count (AMC)and monocyte subpopulation counts at days 60 and 100 were identified based on stem cell source (all P <.01), with more robust recovery in umbilical cord blood (UCB)recipients. We studied monocyte subpopulation recovery at days 28, 60, 100, 180, and 365 post-HCT among 202 patients with hematologic malignancy. We hypothesized that monocyte subpopulation reconstitution would vary based on allogeneic stem cell source and would be associated with outcomes. However, monocytes are heterogeneous and consist of classic (CD14 ++ CD16 - ), intermediate (CD14 + CD16 + ), and nonclassic (CD14 + CD16 ++ )subpopulations, with unique functional properties. Monocyte recovery after hematopoietic cell transplantation (HCT)has been correlated with overall survival (OS).