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To explore the effects of tetra-arsenic tetra-sulfide (As(4)S(4)) in treatment of human chronic myelogenous leukemia K562 cells and its mechanism, trypan blue staining and microculture MTS assay were used to measure the effects of As(4)S(4) on growth inhibition of K562 cells; the morphologic change was determined by Wright's staining assay. The apoptosis rate and cell cycle were detected by flow cytometry; the changes of transcript and protein level were determined by real-time quantitative RT-PCR and Western blot analysis, respectively. The results indicated that As(4)S(4) had significant cytotoxicity on K562 cells. At the concentration of 0.5 micromol/L, the cell viability decreased significantly after being cultured with As(4)S(4) for 24 hours. When the concentration was lower than 0.1 micromol/L, As(4)S(4) had a little effect on K562 cells. The effect of As(4)S(4) on K562 was time- and concentration- dependent. After being cultured with As(4)S(4) at the concentration of 1.0 micromol/L for 24 to 48 hours, K562 cells displayed typical morphological changes of apoptosis. At a concentration greater than or equal to 1.0 micromol/L, As(4)S(4) could induce apoptosis significantly. After 12 hours of incubation with 1.0 micromol/L As(4)S(4), the apoptosis rate increased from (3.47 +/- 0.42)% to (6.16 +/- 0.98%). At the same time, the percentage of cells in G(1) phase decreased from (69.65 +/- 3.24)% to (50.53 +/- 2.86)%, whereas the percentage of cells in G(2)/M phase increased from (9.56 +/- 2.51)% to (12.91 +/- 2.13)%. The mRNA level of Bcl-X(L) and the protein level of pAkt were down-regulated after the inhibition of As(4)S(4), while the mRNA expression of Bcl-2, Bad and Bax had no change. Both of the transcript and protein level of bcr-abl had no change after incubation with As(4)S(4). It is concluded that As(4)S(4) can inhibit the growth of K562 cells efficiently through inducing apoptosis and cell cycle arrest. It seems that As(4)S(4) interferes with pAkt pathway and down-regulates Bcl-X(L), which may be involved in the response of K562 to this agent.

Objective: To investigate the expressions of costimulators on peripheral T and B lymphocytes in patients with idiopathic thrombocytopenic purpura (ITP)., Methods: The expression of B7-CD(28) and CD(40) of peripheral lymphocytes was measured by flow cytometry in 21 ITP patients and 9 normal subjects. The expression of PAIgG was measured by ELISA method., Results: The expression of CD(4)(+)CD(28)(+) was lower in ITP patients than in normal controls, but the expression of CD(86)(+) and CD(86)(+)CD(19)(+) was higher in ITP patients than in normal controls, while the expression of CD(80)(+), CD(40)(+), CD(28)(+), CD(19)(+)CD(86)(+), CD(19)(+)CD(40)(+), CD(4)(+)CD(28)(+)/CD(4)(+), CD(19)(+)CD(80)(+)/CD(19)(+) and CD(19)(+)CD(40)(+)/CD(19)(+) in ITP patients was normal. The PAIgG level was higher in 16 patients with a mean of (184.62 +/- 38.00) ng/10(7) plt. A positive correlation was found between PAIgG and CD(19)(+)CD(86)(+)/CD(19)(+) expression., Conclusion: There is no deficiency in expression of CD(28) on CD(4)(+) T lymphocytes in ITP patients. The change of CD(86) expression on B lymphocytes is possibly involved in pathophysiology of ITP, which may provide a theoretical instruction for ITP patients immunological therapy.