Sodium valproate facilitates the propagation of granulocytic ehrlichiae (Anaplasma phagocytophilum) in HL-60 cells.
As already shown, some inducers of the differentiation of promyelocytic cells along the granulocytic pathway, such as dimethylsulphoxide (DMSO) or all-trans retinoic acid, can enhance propagation of granulocytic ehrlichiae in HL-60 cell cultures. This study was conducted to prove whether sodium valproate, a salt of di-n-propylacetic acid (VPA) known to trigger cellular differentiation in several solid and hematopoietic malignancies is similarly efficient in ehrlichial cultures. Two cell lines derived from HL-60, that is, low-passage undifferentiated HL-60 (HL-60F) and high-passage HL-60 spontaneously differentiated towards monocytic phenotype (HL-60J) were grown in RPMI 1640 medium supplemented with 10% FBS. The respective HL-60F and HL-60J IC50-values for NaVPA were estimated to be 0.8 and 2.2 mM under these culture conditions; to stimulate the differentiation, the respective doses of 0.3 and 1.2 mM were then applied. When the NaVPA-treated cells of both lines were challenged with an ehrlichial laboratory strain (HGE), maintained in splenectomized NMRI mice, the respective 1-2 and < or = 0.1% primary infection rates in HL-60F and HL-60J cultures were observed 3 days post-inoculation. In comparison, only rare (< or = 0.1%) infected HL-60F and no infected HL-60J cells were recorded under the same experimental conditions in untreated control cultures. HGE continuously propagated in NaVPA-supplemented HL-60F cultures remained infectious to mice at least up to the 95th passage (12 months). NaVPA can thus facilitated continuous propagation of granulocytic ehrlichiae in cell cultures without a substantial loss of infectiveness.
Regional Center of Hygiene, Dittrichova 17, 120 00, Prague 2, Czech Republic. zeman3@post.cz
Petir
P
Zeman
Jaroslav
J
Cinatl
Hana
H
Kabickova
D041081:Anaplasma phagocytophilum / Q000187:drug effects* / Q000254:growth & development* / Q000648:ultrastructure; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D008854:Microscopy, Electron; D014635:Valproic Acid / Q000494:pharmacology*
D001426:Bacterial Proteins; D014635:Valproic Acid