中文摘要：

The expression of paired immunoglobin-like receptors A (PIR-A) and B (PIR-B) and their relationship with tolerogenic dendritic cells (T-DC) in mice were investigated. The mouse DCs line, DC2.4 cells were cultured with the recombinant murine interleukin-10 (IL-10) and recombinant human transforming growth factor β1 (TGF-β1) respectively to develop the T-DC and stimulated with lipopolysaccharide (LPS) for 48 h to induce the mature dendritic cells (LPS-DC). Special small interfering RNAs (siRNA) molecule for PIR-B was chemically synthesized and transfected into DC2.4 cells (Si-DC) by lip2000. The expression of PIRs on DC2.4 cells were detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), flow cytometry (FCM) and Western blot. Realtime reverse transcriptase-polymerase chain reaction (Realtime-PCR) was ap- plied for measurement of PIR-A and CD80, CD86, MHC-Ⅱ mRNA expression. The allogeneic stimulating capacity of DCs was measured by mixed lymphocyte reaction (MLR) using 3H-thymidine incorporation test. The concentration of IFN-γ in supernatants of MLR from distinct groups was ana- lyzed by ELISA. The results showed that PIR positive rate was (28.65±8.12)% examined by FCM on DC2.4 cells. PIR positive rate was increased dramatically to (54.21±6.34)%, (58.78±4.70)%, (48.24±6.75)% respectively for IL-10, TGF-β1 and LPS induction (P【0.01), but there was no sig- nificantly different among the three groups (P】0.01). The semi-quantitative RT-PCR and Western blot revealed that IL-10 and TGF-β1 induced the higher PIR-B level and lower PIR-A level. On the contrary, the LPS down-regulated the PIR-B expression and up-regulated the PIR-A expression. Realtime PCR examination demonstrated that PIR-A and co-stimulating molecules such as CD80, CD86 and MHC-Ⅱ were increased significantly after stimulation with LPS. Compared with the DC2.4 cells and the LPS-DC, the T-DCs inhibited alloactived T cell proliferation and down-regulated the IFN-γ secretion in MLR supernatant. Si-DC promot