PERIPHERAL-BLOOD CD34(-MARROW CD34(+) CELLS IN THY-1 EXPRESSION AND CELL-CYCLE STATUS IN NONHUMAN-PRIMATES MOBILIZED OR NOT MOBILIZED WITH GRANULOCYTE-COLONY-STIMULATING FACTOR AND() CELLS DIFFER FROM BONE)OR STEM-CELL FACTOR/

Granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SC F) have been shown to stimulate the circulation of hematopoietic proge nitor cells in both mice and nonhuman primates, We evaluated the immun ophenotype and cell cycle status of CD34(+) cells isolated from the bo ne marrow (BM) and leukapheresis product of cytokine-mobilized nonhuma n primates. CD34(+) cells were isolated from rhesus macaques that had received no cytokine therapy, 100 mu g/kg/d G-CSF, 200 mu g/kg/d SCF, or a combination of both 100 mu g/kg/d G-CSF and 200 mu g/kg/d SCF as a subcutaneous injection for 5 days. BM was aspirated before (day 0) a nd on the last day (day 5) of cytokine administration. On days 4 and 5 , peripheral blood (PB) mononuclear cells were collected using a novel method of leukapheresis. Threefold more PB mononuclear cells were col lected from animals receiving G-CSF alone or G-CSF and SCF than from a nimals that had received either SCF alone or no cytokine therapy. CD34 (+) cells were positively selected using an immunoadsorptive system fr om the BM, PB, and/or leukapheresis product. Threefold and 10-fold mor e CD34(+) cells were isolated from the leukapheresis product of animal s receiving G-CSF or G-CSF and SCF, respectively, than from animals re ceiving no cytokine therapy or SCF alone, The isolated CD34(+) cells w ere immunophenotyped using CD34-allophycocyanin, CD38-fluorescein isot hiocyanate, and Thy-l-phycoerythrin. These cells were later stained wi th 4',6-diamidino-2-phenylindole for simultaneous DNA analysis and imm unophenotyping. BM-derived CD34(+) cells did not differ significantly in cell cycle status and Thy-1 or CD38 phenotype before or after G-CSF and/or SCF administration. Similarly, CD34(+) cells isolated from the leukapheresis product did not differ significantly in immunophenotype or cell cycle status before or after G-CSF and/or SCF administration. However, there were consistent differences in both immunophenotype an d cell cycle status between BM- and PB-derived CD34(+) cells, CD34(+) cells isolated from the PB consistently had a smaller percentage of ce lls in the S+G2/M phase of the cell cycle and had a higher percentage of cells expressing Thy-1 than did CD34(+) cells isolated from the BM. A greater proportion of PB-derived CD34(+) cells were in the S+G2/M p hase of the cell cycle after culture in media supplemented with interl eukin-6 and SCF. However, culturing decreased the proportion of CD34() cells expressing Thy-1. (C) 1996 by The American Society of Hematolo gy.