Role of human interleukin-9 as a megakaryocyte potentiator in culture.
OBJECTIVE
This study investigated the effect of interleukin-9 (IL-9) on the proliferation and differentiation of human colony-forming unit megakaryocytic progenitor cells (CFU-Meg).


METHODS
Peripheral blood-derived CD34(+)IL-6R(-) cells were sorted and cultured in the presence of IL-9, erythropoietin (Epo), stem cell factor (SCF), and thrombopoietin (TPO) alone or in combination. The number of pure and mixed megakaryocyte colonies, the size of pure megakaryocyte colonies, the ploidy distribution of megakaryocytes, and proplatelet formation were investigated.


RESULTS
Apart from TPO, no single factor could support CFU-Meg-derived colony formation, but each two-factor combination among IL-9, Epo, and SCF supported a few CFU-Meg colonies. Interestingly, the combination of Epo+SCF+IL-9 induced four to six times as many CFU-Meg colonies as any of the two-factor combinations. Neutralizing monoclonal antibodies (mAbs) for IL-9 receptor and c-kit completely abolished this synergistic effect. In contrast, addition of neutralizing anti-c-Mpl or anti-CXCR4 Abs did not influence colony formation, indicating that this synergistic effect was independent of TPO or SDF-1. Moreover, the endogenous production of TPO by cultured CD34(+)IL-6R(-) cells in the presence of Epo+SCF+IL-9 was ruled out by reverse transcriptase polymerase chain reaction for TPO mRNA. Interestingly, the combination of TPO, Epo, SCF, and IL-9 supported the largest number of pure and mixed megakaryocyte colonies, suggesting that this combination of cytokines might recruit primitive megakaryocytic as well as multipotential progenitors. This combination also potently enhanced proplatelet formation compared with TPO alone or a combination of Epo, SCF, and IL-9.


CONCLUSIONS
This study demonstrated for the first time that human IL-9 can potentiate human megakaryocytopoiesis in the presence of Epo and/or SCF.
Fujiki
Hiroshi
H
Department of Hygiene, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyoku, Kyoto 602-8566, Japan.
Kimura
Takafumi
T
Minamiguchi
Hitoshi
H
Harada
Sachio
S
Wang
Jianfeng
J
Nakao
Makoto
M
Yokota
Shouhei
S
Urata
Yoji
Y
Ueda
Yuji
Y
Yamagishi
Hisakazu
H
Sonoda
Yoshiaki
Y
D001792:Blood Platelets / Q000166:cytology; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004357:Drug Synergism; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects; D004921:Erythropoietin / Q000494:pharmacology; D006801:Humans; D016906:Interleukin-9 / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D008533:Megakaryocytes / Q000166:cytology*; D019089:Stem Cell Factor / Q000494:pharmacology; D013926:Thrombopoietin / Q000494:pharmacology
D016906:Interleukin-9; D019089:Stem Cell Factor; D004921:Erythropoietin; D013926:Thrombopoietin