Abstract: Objective: To investigate the characteristics of expression of Th1 cytokines interleukin-2(IL-2) and interferon-γ(IFN-γ) of human peripheral γδT cells stimulated with different stimuli.Methods: Human peripheral blood mononuclear cells(PBMCs) were stimulated with phorbol 12-myristate 13-acetate(PMA) and ionomycin,combined with or without anti-CD28 mAb for 6 to 8 h;or stimulated with Mtb-Ag and cultured in IL-2 containing medium for 3 to 8 days,the intracellular cytokines IL-2 and IFN-γ in γδ and αβT cells were detected by flow cytometry.Results: The percentages of IL-2 secreting cells of γδT cells among PBMCs stimulated with PMA+ionomycin were very low (1.1%);compared with that of αβT cells(14.0%).The percentages of IFN-γ-secreting cells of γδ and αβT cells among PBMCs stimulated with stimuli as above were 56.1%,and 8.5%,respectively.Upon the stimulation of PBMCs with PMA+ Ionomycin combined with anti-CD28mAb,the percentages of IL-2 secreting αβT cells increase to 31%,but IL-2 secreting γδT cells were not significantly increased.Meanwhile the percentages of IFN-γ-secreting γδ and αβT cells increase to 77.4% and 15.4%,respectively.After PBMCs stimulated with Mtb-Ag and cultured in IL-2 containing medium,the percentage of IL-2 producing cells γδT cells were detected only on day 3 and later,increased markedly to a peak on day 6,and thereafter declining to a lower level.Conclusions: Stimulated with PMA+ionomycin combined with or without anti-CD28mAb, the human γδT cells among PBMCs default produced of IFN-γ while αβT cells default produced of IL-2. Activated with Mtb-Ag and cultured in presence of IL-2 from 3 to 6 days, γδT cells were also able to produce IL-2.