Separation of chemotherapy plus G-CSF-mobilized peripheral blood mononuclear cells by counterflow centrifugal elutriation: In vitro characterization of two different CD34(+) cell populations

Counterflow centrifugal elutriation (CCE) has been extensively employed in T cell depletion of bone marrow cells for allografting. Nevertheless very little is known about CCE properties of mobilized hematopoietic progenitors. In this study five leukapheresis products collected after chemotherapy and G-CSF from patients with non-Hodgkin's lymphoma were elutriated. Two mononuclear cell fractions were obtained containing smaller and less dense cells (lymphocyte fraction) and larger and denser cells (monocyte fraction), respectively, The presence of immature CD34(+) progenitor cells, not co-expressing CD33, CD38 and HLA-DR antigens, was demonstrated in both cell fractions, CD34(+) cells were isolated from each fraction and grown in various culture conditions (CPU-GM and BFU-E assay, blast cell colony assay, cytokine supplemented liquid culture), CD34(+) cells isolated from the monocyte fraction showed a longer lasting expansion in liquid culture and a higher number of blast cell colonies than CD34(+) cells selected from the lymphocyte fraction, Moreover a significant reduction of T cell number was obtained in the monocyte fraction, These data suggest that chemotherapy plus G-CSF-mobilized progenitor cells show a characteristic behavior when subjected to CCE, allowing an efficient T cell depletion without losing more immature progenitors.