中性粒细胞抑制人单个核细胞释放TNF-α及其机理的研究

目的:探讨人中性粒细胞(PMNs)对人外周血单个核细胞(PBMCs)释放TNF-α的影响及其作用机理。方法:采集健康供血者的新鲜外周静脉血,以葡聚糖沉淀和密度梯度离心法分离其PMNs和PBMCs,将PMNs细胞与PBMCs细胞按2:1的数量比与脂多糖共同培育后,分别采用酶联免疫吸附法测定培养上清的TNF-α浓度,并用流式细胞术测定结合荧光标记脂多糖的单核细胞的百分率及单核细胞表面平均荧光强度。结果:PMNs在细菌脂多糖刺激下不释放TNF-α,PMNs可以抑制PBMCs释放TNF-α,其抑制作用具有细胞特异性;经多聚甲醛固定的PMNs仍具有上述的抑制作用。流式细胞术结果显示PMNs并不影响单核细胞与脂多糖结合。结论:PMNs可抑制人PBMCs释放TNF-α,其机理可能是PMNs干扰脂多糖激活PBMCs的信号转导过程,抑制细菌脂多糖对其的活化,从而下调TNF-α的释放。

The inhibition by polymorphonuclear leukocytes of TNF - α release from human mononuclear cells and its mechanism

AIM:To investigate the effect of human polymorphonuclear leukocytes (PMNs) on the release of TNF-α by the human peripheral blood mononuclear cells (PBMCs) and to elucidate its mechanism. METHODS:Human PMNs and PBMCs were isolated from the venous blood of healthy donors by dextran sedimentation and density gradient centrifugation. After the cells were cocultured at the ratio of 2:1 in the presence of lipopolysaccharide (LPS), the concentration of TNF-α in the supernatant was measured by enzyme-linked immunosorbent assay. The binding rate of monocytes with the fluorescein isothiocyanate-labeled LPS (FITC-LPS) and the mean surface fluorescence intensity of monocytes were analyzed by flow cytometry.RESULTS:PMNs do not produce detectable TNF-α in the presence of LPS. PMNs were capable of inhibiting the TNF-α release from PBMCs (P＜0.05). This inhibitory effect was further confirmed to be PMNs specific as paraformaldehyde-fixed PMNs still demonstrated the same inhibition (P＜0.05) and red blood cells showed no effect. Flow cytometry analysis showed that PMNs did not block the binding of LPS with PBMCs.CONCLUSION:PMNs suppressed the TNF-α release by PBMCs via cell-to-cell interaction. PMNs may interfere with the signal transduction pathway through which LPS activates PBMCs,thus attenuating the response of PBMCs to LPS and downregulating the TNF-α release.