Graft engineering of G-CSF-mobilized allogeneic leukapheresis products by counterflow centrifugal elutriation after CD34 column adsorption

A major hindrance to the use of PBSC in allogeneic transplantation is the high rate of contamination with T lymphocytes, resulting in a considerable risk of GvHD. Natural killer (NK) cells are active against tumor cells but do not contribute to the development of GvHD. After adsorption of CD34+ cells of mobilized allogeneic leukapheresis products on a Ceprate column, we studied the separation of CD34 unadsorbed cells by counterflow centrifugal elutriation (CCE). Up to 1.0 x 10(10) cells were clearly separated into lymphocytes (fractions 110 and 140 ml/min), monocytes, and polymorphonuclear cells (fraction rotor off). Characterized by flow cytometry, T cells were distributed nearly equal to fractions 110 and 140. NK cells were concentrated 3.4-fold in fraction 140 as compared with the unseparated cells. The ratio of NK cells/T cells was improved by 33%. These results indicate that CCE is an effective method to enrich NK cells and to reduce T cells in stem cell separation products. Therefore, it is an option for adoptive therapy of cancer patients after transplantations (e.g., CML in relapse).