PROGENITOR CELLS PURGING - NEGATIVE SELECTION

Disease relapse after autologous bone marrow transplantation (ABMT) ma y arise from residual tumor in the recipient and/or from cancer cells that are reinfused. The aim of purging by negative selection is to rem ove tumor cells from the marrow without adversely affecting the engraf tment potential of the normal cell. We report the results of a study o n fifty-six patients (pts) with non Hodgkin's lymphoma or acute leukem ia submitted to ABMT after immunomagnetobead (IMB) purging (11 pts), M aphosphamide purging (31 pts) and no purging (14 pts). The IMB procedu re involved one incubation of 3 monoclonal antibodies (CD10, CD19 and CD22) and two incubations with magnetic beads (Dynabeads M-450). The m edian recovery of mononuclear cells and CFU-GM was 40% and 45% after I MB purging and 84% and 5% after Maphosphamide purging respectively. Th e rate of leukocyte, neutrophils and platelets recovery following ABMT was similar in the three groups of pts, although platelet recovery wa s slow in patients received graft purged with Maphosphamide. Our study confirms the clinical feasibility of the IMB procedure, but only rand omized studies will be able to definitively address the question of th e clinical utility of purging.