ABSTRACT
Objective To study the In vitro expansion of human CD8+ CD28- suppressor T cells and their immunological regulatory effect.Methods Human CD8 + CD28- suppressor T cells were expanded in vitro driven by the combination of cytokines and allogeneic antigen presenting cells (APCs).Flow cytometry was used to assess the development of CD28- subpopulation.Expanded CD8+ CD28- T cells were isolated by immunomagnetic microspheres and then added as third part modulators into mixed lymphocyte culture to assess their immunological regulatory characteristics.Results The combination of cytokines included IL-2,IL-7 and IL-15 and allogeneic APCs could increase the portion of CD8 + CD28- T cell subtype,and expansion fold of CD8+ CD28- T cell subtype was significantly increased as compared with others (P＜0.05).Expanded CD8+ CD28- T cells could suppress the proliferation of CD4+ T cells stimulated by allogeneic APCs.Moreover,this suppression had antigen specificity.Conclusion Human CD8 + CD28- suppressor T cells can be in vitro expanded in large amounts driven by the combination of cytokines and allogeneic APCs.Expanded CD8 + CD28- T cells in this study have antigen specific regulatory characteristics.
ABSTRACT
Objective To investigate the possibility of DCs transfected with CTLA4Ig cDNA by retrovirus vector to induce antigen specific hyporesponsiveness.Methods The modified DCs(CTLA4Ig-DCs) were prepared by transferring the DCs from cultured rat BM cells with the constructed retro-virus CTLA4Ig vector.The CTLA4Ig gene expression was detected on the prepared DCs by RT-PCR and Dot-ELISA methods.The influence of the modified DCs on mixed lymphocyte reaction(MLR) intensity was determined by T cell proliferation.Results The CTLA4Ig gene could be transferred successfully to DCs by retrovirus vector,which was confirmed by RT-PCR and Dot-ELISA methods.As compared with control group,DCsRev could significantly and antigen-specifically inhibit MLR in vitro in a dose-and time-dependent manner.The number of DCRev from 10~(3) to 10~(4) could reach the maximal inhibition by(69.12 %).On the other hand,the inhibition capacity of DCsRev was increased from(48 h) to 12 h prior to adding stimulating cells and the maximal inhibition was(98.3 %) at(12 h).Analysis of T cell proliferation revealed that donor-specific inhibition could be induced by DCsRev in an ex-vivo model.But this kind of inhibition was not lifetime.Conclusions The CTLA4Ig gene could be transferred successfully to DCs by retrovirus vector.This kind of DCs lost capacity of stimulating MLR,and could inhibit T cell proliferation,which might be responsible for the antigen-specific suppression induced by DCsRev.