AIM: To study the effect of IL-12 on T lymphocytes apoptosis, the expression of Fas/FasL and TNFR/TNF?. METHODS: Terminal dUTP nick end labeling(TUNEL) and Annexin V assay were used. Anti-TNFR were labeled with FITC, anti-CD95 was labeled with PE and Anti-FasL with biotin. Three kinds of T cells (HTB176,TIB152 and human normal T cells) were analysed through flow cytometry. RESULTS: At 1st hour after being treated with IL-12, the expression of FasL protein and FasL mRNA in HTB176 and TIB152 began to increase and reached peak value in 24 hours. In the normal T cells, FasL just began to increase in 1 hour and maintained stability in 6, 12 and 24 hours through the later experiment period. All three kinds of T cells displayed no change in the expression of CD95 and TNFR/TNF? under the stimulation of IL-12. CONCLUSION: Expression of such apoptosis regulating factors were different in the apoptosis of T cells induced by IL-12.

Objective To explore the signaling pathway of apoptosis induced by Paclitaxel (PTX) in leukemia cells and the chemosensitizing effect of adding short hairpin RNA(shRNA) on PTX,which targets the silencer of death domains(SODD).Methods After being treated with PTX,the expressions of SODD,B-cell lymphoma/leukemia-2 (Bcl-2),nuclear factor kappa B (NF-κB) and Caspase-3 proteins in Jurkat cells were determined by Western blot ;the shRNA-SODD vectors were constructed and transfected into Jurkat cells by electroporation,and then G418 was used to select the stable tranfected cell line expressing the shRNA-SODD recombinant plasmids.The incidence of cell apoptosis induced by PTX was determined by flow cytometry labeled with propidium iodide.Results During the process of inducing apoptosis of Jurkat cells,PTX could significantly down-regulate the expressions of SODD and Bcl-2 proteins,degrade Caspase-3 and activate NF-κB.The apoptotic sensibility of Jurkat cells transfected with shRNA-SODD to PTX was significantly increased compared with the control group,and the difference was statistically significant (F =10.35,P ＜ 0.05).Conclusions PTX can effectively induce apoptosis of Jurkat cells.Perhaps,SODD/Bcl-2 represents a specific apoptotic signaling pathway of PTX in leukemia cells and this apoptotic signaling pathway is Caspase-3-dependent,in which the function of NF-κB is to modulate the correlative apoptotic factors.Inhibiting the expression of SODD through transfecting shRNA-SODD vectors can significantly increase the apoptotic sensibility of leukemia cells to PTX.