Collection and analysis of peripheral blood mononuclear cells during haemopoietic recovery following PBSCT for CML: autografting as an in vivo purging manoeuvre?

A 47-year-old man with a 2-year history of Philadelphia chromosome-positive chronic phase (CP) chronic myeloid leukaemia (CML) underwent autologous PBSCT. During the period of haemopoietic reconstitution he underwent five leucapheretic (LP) harvests yielding a total of 2.6 x 10(6)/kg CD34+ cells. Cytogenetic analyses revealed 94, 83, 83, 96 and 85% Ph negativity respectively for the five harvests. RT-PCR analyses for BCR-ABL performed on randomly picked CFU-GM from the five LP products were negative in all cases. These observations suggest that the majority of harvested cells, including the more primitive clonogenic cells, were BCR-ABL (Ph) negative and presumably were not part of the leukaemic clone. These findings support the notion that autologous PBSCT in CML whilst serving as a therapeutic manoeuvre may also facilitate the collection of non-leukaemic progenitor cells for further transplantation procedures.