Inhibitory effects of indoleamine 2,3-Dioxygenase-transfected dendritic cells and Tryptophan catabolites on proliferation of CD4 + T lymphocytes

Abstract

Objective To demonstrate the inhibitory effect of indoleamine 2,3-dioxygenase (IDO)-transfected dendritic cells (DCs) and Tryptophan catabolites on proliferation of CD4 +T lymphocytes.Methods IDO cDNA was obtained and inserted into eukaryotic expression vector pEGFP-N1 to construct the recombinant expression plasmid pEGFP-N1-IDO.The recombinant plasmid was transfected into mouse DCs by GenePORTER 3000.IDO expression level was detected by using real-time quantitative polymerase chain reaction (Real-time PCR) and immunocytochemistry.The transfected DCs with or without Tryptophan catabolites and 1-mythotryptophan were co-cultured with allogeneic CD4 +T lymphocytes.Stimulation index (SI) was analysed by mixed lymphocyte reaction (MLR).Results pEGFP-N1-IDO was successfully generated and verified by sequencing.IDO mRNA expression level was significantly higher in pEGFP-N1-IDO-transfected DCs group (0.1550 ±0.0124) than that in DCs group (0.1197 ±0.0463) or pEGFP-N1-transfected DCs group (0.1152 ± 0.0260).Positive staining was found in the pEGFP-N1-transfected DCs by immunocytochemistry.SI in pEGFP-N1-IDO-transfected DCs group (2.8640 ± 0.1459) was significantly lower than that in non-transfected group (3.3040 ± 0.2394),pEGFP-N1-transfected DCs group (3.2340 ±0.1862) and 1-methyl-tryptophan (1-MT) addition group (3.1900 ±0.2906).The inhibitory concentrations of Tryptophan catabolites in pEGFP-N1-IDO-transfected DCs group were lower significantly than those in non-transfected group or pEGFP-N1-transfected DCs group.Conclusion pEGFP-N1-IDO-transfected DCs can express functional IDO.The pEGFP-N1-IDO-transfected DCs and tryptophan catabolites both can inhibit the proliferation of CD4 + T lymphocytes. Key words: Indoleamine 2,3 dioxygenase; Vector pEGFP-N1-IDO; Tryptophan catabolites; Dendritic cells