来源于CD14^+的树突细胞分化过程中膜脂分子运动及蛋白质构象的变化

Alterations in Membrane Lipid Dynamics and Protein Conformations of CD14^+Monocytes Differentiation into Dendritic Cells

目的:树突细胞(D endritic Ce lls,DC)是免疫系统中功能最强大的抗原呈递细胞(Antigen Presen-ting Ce lls,APC),它具有独特的向T细胞呈递抗原的能力。为了研究DC分化过程中细胞膜性质和细胞蛋白质构象的变化,以对其基本生物学特性有更好的理解。方法:用免疫磁珠从人外周血单个核细胞分离得到CD14+单核细胞,用人GM-CSF和IL-4诱导其分化为未成熟的DC后,加入TNF-α使其成熟。用荧光偏振和傅里叶变换红外光谱技术研究各发育阶段细胞膜流动性及其蛋白二级结构的变化。结果:在CD14+单核细胞分化为未成熟和成熟DC过程中,细胞膜的流动性和蛋白质的α-螺旋、β-片层、β-弯曲和无规卷曲等二级结构均发生了明显改变。结论:成熟DC的膜脂分子运动比单核细胞和未成熟DC更为活跃,同时蛋白质的构象的主要成分也显著减少。

Objective： The capacity of dendritic cells （DCs） to initiate immune responses is dependent on their specialized migratory, stimulation and tissue homing properties. To gain further insights into the function of DCs, we applied biophysical methods to study the differentiations of CD14^＋ monocytes into DCs. Methods： CD14^＋ monocytes isolated from human peripheral blood by immune magnetic beads were cultured with 50 mg/L rhGM-CSF1 000 U/ml and rhIL-4 for 7 days. Then, a large number of DCs was gained, and these cells were maturated under the effect of TNF-α. The measurements of fluorescence polarization and fourier transformed infrared spectrum were performed to observe the cell membrane fluidity and the change of protein conformation in different stages of the cell differentiation. Results： Significant changes of motilities of membrane lipid molecules and protein conformation of cells were observed in the process of differentiations of CD14^＋ monocytes into DCs. Conclusions： The motions of membrane lipid molecule of mature DCs are more dynamic than that of monocytes and immture DC, and the important components of protein conformation also markedly decrease in mature DCs.