Monocyte engraftment dynamics and flow cytometric analysis in allogeneic and autologous peripheral blood stem cell
Delal Melik1, Pelin Aytan2, Cemil Gulum3
1Department of Internal Medicine, Faculty of Medicine, Mersin University, Mersin, Türkiye.
Background:
Hematopoietic stem cell transplantation (HSCT) success relies on timely engraftment and immune reconstitution. While neutrophil and platelet recovery are well-established clinical endpoints, the dynamics of monocyte engraftment and their relationship with hematopoietic recovery remain insufficiently characterized.
Methods:
In this prospective observational study, 56 patients undergoing autologous (n = 32) or allogeneic (n = 24) peripheral blood stem cell transplantation were enrolled. Pre-engraftment monocyte peak day was defined based on serial complete blood counts. Flow cytometric analysis was performed at the time of monocyte engraftment to assess monocyte (CD14/CD16) and lymphocyte subsets. Associations between monocyte dynamics and neutrophil and platelet engraftment were evaluated using correlation and multivariable regression analyses.
Results:
Allogeneic recipients demonstrated significantly delayed neutrophil engraftment compared to autologous patients (p=0.003). Pre-engraftment monocyte peak day was strongly correlated with neutrophil engraftment (ρ = 0.83, p < 0.001) and moderately correlated with platelet engraftment (ρ = 0.46, p = 0.001). In multivariable analyses, monocyte peak timing remained independently associated with both neutrophil (B = 0.87, p < 0.001) and platelet recovery (B = 1.53, p = 0.015), whereas CD34⁺ cell dose showed no independent association. Flow cytometric analysis demonstrated predominance of CD14⁺ monocytes during early engraftment. Despite elevated inflammatory markers in patients with complications, engraftment kinetics remained comparable.
Conclusions:
Pre-engraftment monocyte dynamics are strongly associated with subsequent hematopoietic recovery and may serve as an early indicator of engraftment following HSCT. These findings support the potential utility of monocyte-based monitoring in post-transplant care and highlight the need for further studies to validate their prognostic value.
