Intracellular disposition of fludarabine triphosphate in human natural killer cells.
OBJECTIVE
Fludarabine is a key component of several reduced-intensity conditioning regimens for hematopoietic cell transplantation (HCT). Shortly after reduced-intensity conditioning, the percent of donor natural killer (NK) cells has been associated with progression-free survival. Insufficient suppression of the recipient's NK cells by fludarabine may lead to lower donor chimerism; however, the effect of fludarabine upon NK cells is poorly understood. Thus, in purified human NK cells we evaluated the uptake and activation of fludarabine to its active metabolite, fludarabine triphosphate (F-ara-ATP), and assessed the degree of interindividual variability in F-ara-ATP accumulation.


METHODS
Intracellular F-ara-ATP was measured in purified NK cells isolated from healthy volunteers (n = 6) after ex vivo exposure to fludarabine. Gene expression levels of the relevant transporters and enzymes involved in fludarabine uptake and activation were also measured in these cells.


RESULTS
F-ara-ATP accumulation (mean +/- SD) was 6.00 +/- 3.67 pmol/1 x 10(6) cells/4 h, comparable to average levels previously observed in CD4(+) and CD8(+) T-lymphocytes. We observed considerable variability in F-ara-ATP accumulation and mRNA expression of transporters and enzymes relevant to F-ara-ATP accumulation in NK cells from different healthy volunteers.


CONCLUSIONS
Human NK cells have the ability to form F-ara-ATP intracellularly and large interindividual variability was observed in healthy volunteers. Further studies are needed to evaluate whether F-ara-ATP accumulation in NK cells are associated with apoptosis and clinical outcomes.
Woodahl
Erica L
EL
Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
Wang
Joanne
J
Heimfeld
Shelly
S
Sandmaier
Brenda M
BM
McCune
Jeannine S
JS
D015720:5'-Nucleotidase / Q000235:genetics / Q000378:metabolism; D001088:Arabinonucleotides / Q000378:metabolism*; D033721:Equilibrative Nucleoside Transporter 1 / Q000235:genetics / Q000378:metabolism; D033722:Equilibrative-Nucleoside Transporter 2 / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism
D001088:Arabinonucleotides; D033721:Equilibrative Nucleoside Transporter 1; D033722:Equilibrative-Nucleoside Transporter 2; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; C438649:SLC29A1 protein, human; C438654:SLC29A2 protein, human; C065171:cif nucleoside transporter; C034957:2-fluoro-araATP; D015720:5'-Nucleotidase; C508048:NT5C2 protein, human
Cancer Chemother Pharmacol. 2009 Feb;63(3):391-401
18398611
Blood. 2008 Jan 1;111(1):446-52
17916744
Cancer Chemother Pharmacol. 1996;37(5):445-50
8599867
J Chromatogr B Analyt Technol Biomed Life Sci. 2005 Jun 25;820(2):243-50
15899377
Oncology (Williston Park). 2003 Jan;17(1):94-100; discussion 103-7
12599934
Biol Blood Marrow Transplant. 2009 May;15(5):580-8
19361750
Leukemia. 2006 Oct;20(10):1701-5
16888618
Cell Immunol. 1990 Oct 15;130(2):513-9
1698564
Leukemia. 2006 Oct;20(10):1690-700
16871276
Biol Blood Marrow Transplant. 2007 Jul;13(7):844-52
17580263
Pharmacol Ther. 1991;49(3):239-68
1675805
Biochem Pharmacol. 2006 Mar 14;71(6):882-90
16436271
Blood. 1998 Feb 1;91(3):756-63
9446633
Leukemia. 2002 Apr;16(4):753-4
11960363
Biochem Pharmacol. 2003 Dec 1;66(11):2185-91
14609743
J Clin Oncol. 2005 Mar 20;23(9):1993-2003
15774790
Blood. 2003 Mar 15;101(6):2328-34
12411296
Cell Immunol. 1990 Sep;129(2):321-8
1696525
Clin Pharmacokinet. 2002;41(2):93-103
11888330