Single leukapheresis products collected from healthy donors after the administration of granulocyte colony-stimulating factor contain ten-fold highernumbers of long-term reconstituting hematopoietic progenitor cells than conventional bone marrow allografts

Cytokine-mobilized peripheral blood progenitor cells (PBPCs) have been used successfully for hematopoietic reconstitution following allogeneic transpl antation. The ease of harvest, the faster engraftment and the high yield of CD34(+) cells have made this source of hematopoietic progenitor cells (HPC s) an attractive alternative to bone marrow (BM), In the present study we c ompared the engraftment potential of conventional BM allografts and single leukapheresis products (LPs) collected fi om healthy donors following the a dministration of granulocyte colony-stimulating factor (G-CSF), For this, l ineage-committed and primitive HPCs were assessed by how cytometry and by c olony- and cobblestone area-forming cell (CFC, CAFC) assays, Mean numbers o f CD34(+) cells in LPs (n = 11) were similar to that of BM grafts (n = 12) (278 +/- 57 vs 227 +/- 34 x 10(6) CD34(+) cells), The frequencies of CFCs, week 5 CAFCs and week 8 CAFCs were 1.6-, 8.4- and 10.3-fold higher in the C D34(+) compartment of mobilized blood than that of marrow, resulting in sig nificantly higher yields of clonogenic HPCs in LPs when compared to BM graf ts, We conclude that G-CSF preferentially mobilizes clonogenic progenitors capable of short- and, in particular, longterm reconstitution, and that the engraftment potential of single LPs is superior to that of BM allografts, Hence, the use of PBPCs may be favorable for protocols that include graft m anipulations with expected cell loss leg T cell depletion, CD34(+) selectio n). PBPCs may also be advantageous for gene therapy trials due to their hig h numbers of potential target cells leg CAFCs).