Effects of CD4 + CD25 + Treg on the killing effects of tumor-specific cytotoxicity of CTL

Abstract

Objective To explore the killing effects of CD4 + CD25 + Treg on tumor-specific cytotoxicity of cytotoxic T lymphocyte (CTL) to B16 Melanoma and the action mechanism.Methods Eighty C57BL/6 mice were randomly divided into three experimental groups and one control group (n = 20 each group).Mononuclear cells were isolated from spleen tissues of the mice,and CTLs were prepared by using DCs loaded with B16 tumor antigens.Tumor inhibition rate was evaluated by using methyl thiazol tetrazolium (MTY) assay in vitro after deletion of CD4 + CD25 + Treg by using MACS,and the secretion levels of interleukin-2 (IL-2) and interferon-γ (IFN-γ) in the supernatant of the cell culture were measured by using enzyme linked immunosorbent assay (ELISA).Results Tumor inhibition rate in three experiment groups was significantly higher than that in control group ( P ＜ 0.05 ).Tumor inhibition rate in groups A and B with a deletion of CD4 + CD25 + Tregs was significantly increased as compared with group C without deletion of Tregs ( P ＜ 0.05 ),but no significant difference was found between groups A and B with deletion of Tregs before and after the culturing ( P ＞ 0.05 ).The difference in the IL-2 and IFN-γwas the same as the tumor tumor inhibition effeciency of antigen-specific CTLs,which might be a new way to breakdown the tumor immune tolerance. Key words: T cell; Dendritic cell; Interleukin-2; Interferon-γ; Immune tolerance