[Apoptosis of human leukemia K562 cell in vitro induced by Toxoplasma gondii].
OBJECTIVE
To investigate whether the Toxoplasma gondii can inhibit proliferation of human leukemia K562 cells and/or induce apoptosis of the cells in vitro. Methods K562 cells (5x10(4)/ml) were harvested at mid-exponential phase and planted in 96 well plates with 100 microl each and in 50 ml culture bottles, 1.5 ml each. The cells were treated for 48 hours with different concentration of Toxoplasma tachyzoites. Growth inhibition rate was measured with MTT method. Apoptosis was detected through following ways: fluorescence microscopy with Hoechst 33 258 staining was used for observing the change of cell morphology, agarose electrophoresis was used to detect the DNA changes and FCM was used to observe sub-diploid.


RESULTS
Toxoplasma can inhibit proliferation of K562 cells. K562 cells treated with Toxoplasma presented an inhibition rate of 17%, 28%, 48%, 50% and 55% under the tachyzoite concentration of lxl0(4), 2x10(4), 4x 10(4), 8x10(4) and 16xl0(4)/ml respectively, with a significant difference to the control (t=3.606, 5.918, P<0.05; t=9.171, 7.841 and 7.067, P<0.01). Cell contraction and apoptotic bodies were observed under fluorescence microscope. DNA fragment was shown through agarose electrophoresis. Flow cytometric analysis showed an apoptosis peak at 48h. The apoptosis rate was 5.53%, 7.12%, 10.34%, 21.14% and 29.68% respectively.


CONCLUSIONS
Toxoplasma gondii inhibits proliferation and induces cell apoptosis in K562 cells in vitro.
Zhang
Xiu-chang
XC
Dapartment of Technology, Hebei North University, Zhangjiakou 075000, China.
Cai
Nian-guang
NG
Sun
Li
L
Luo
Qiang
Q
An
Fang
F
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D049109:Cell Proliferation; D006790:Host-Parasite Interactions; D006801:Humans; D020014:K562 Cells; D007938:Leukemia / Q000469:parasitology / Q000473:pathology; D014122:Toxoplasma / Q000502:physiology*