IL-10诱导小鼠树突状细胞耐受的分子机制

目的：研究白细胞介素-10 (interleukin-10，IL-10)诱导小鼠来源的树突状细胞(DC)耐受及其与配对免疫球蛋白样受体（PIR-A/B）的关系。方法: 以IL-10（20 μg/L）诱导小鼠来源的树突状细胞系（DC2.4）6 d，即IL-10-DC组，脂多糖（LPS）刺激其48 h为成熟DC2.4细胞（LPS-DC），体外化学合成特异性针对PIR-B的小干扰RNA片段，以脂质体2 000转染IL-10组（Si-DC组）。分别应用半定量RT-PCR和流式细胞仪（FCM）检测DC2.4、IL-10组、LPS组及Si-DC组细胞PIR-A/B的表达。以［3H］-TdR标记法检测上述各组细胞刺激同种异体淋巴细胞的增殖反应(MLR)，ELISA方法测混合培养上清中IFN-γ的水平变化。结果: RT- PCR结果表明，IL-10诱导PIR-B表达升高、PIR-A表达下降，LPS则下调PIR-B、上调PIR-A的表达。FCM检测IL-10组和LPS组的PIR-A/B胞外区PIR表达均升高，且前者明显高于后者。同正常DC2.4和LPS组相比，IL-10可抑制MLR，小干扰RNA沉默PIR-B表达可增强MLR，伴随MLR反应上清中IFN-γ的水平升高。结论: IL-10诱导DC高度表达免疫抑制性受体PIR-B，使其获得耐受，上调PIR-B的表达是IL-10诱导DC耐受的分子机制之一。

The molecular mechanism of tolegenic dendritic cells induced by IL-10 in mouse

AIM:To investigate the relation of tolerogenic dendritic cells (DC) induced by interleukin-10 (IL-10) and the paired immunoglobin-like receptor (PIR) A and B (PIR-A and PIR-B) in mouse. METHODS:The mouse dendritic cell line, DC2.4 cells were cultured with the IL-10 to develope the IL-10-DC and were stimulated by lipopolysaccharide (LPS) for 48 h to induce the mature dendritic cells (LPS-DC). Special small inference RNA (siRNA) molecule of PIR-B was chemically synthesized and was transfected into IL-10-DC by Lipofectamine 2000 (Si-DC). The expression of PIR A and PIR B on DC2.4 cells were measured by semi-quantitative RT-PCR and flow cytometry (FCM). The allogeneic stimulating capacity of DC 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 analyzed by ELISA. RESULTS:IL-10 up-regulated the PIR-B and down-regulated the PIR-A by semi-quantitative RT-PCR. On the contrary, LPS down-regulated the PIR-B expression and up-regulated the PIR-A expression. The expression of PIR, which is the common extra-membrane of PIR-A and PIR-B, was increased in both the IL-10-DC and the LPS-DC groups by FCM detection, but the higher expression was found in IL-10-DC group than that in LPS group. The IL-10 induced the higher PIR-B expression, inhibited allogenetic T cell proliferation and down-regulated the IFN-γ secretion. Special siRNA molecules of PIR-B in IL-10 group promoted the T cell proliferation and enhanced the IFN-γ secretion in MLR. CONCLUSION:IL-10 up-regulates the PIR-B expression and makes DC tolerance. Up-regulated PIR-B expression may be the molecular mechanism of tolerogenic dendritic cells induced by IL-10 in mouse.