英国一项最新研究显示，人体中名为自然杀伤细胞的免疫细胞拥有长绳状的“远程攻击武器”，可将试图逃跑的目标细胞抓回或远程杀死。这一发现将有助于研发提高人体免疫力的药物。
英国帝国理工学院等机构的研究人员在新一期美国PNAS上报告说，通过使用一种细胞染色技术，可以在显微镜下看到自然杀伤细胞与其他细胞间形成的细丝状“膜纳米管”。通常，自然杀伤细胞会附着到发生病变的目标细胞上并将其杀死，但有时候目标细胞在接触之后会试图逃跑，观测显示，这时候自然杀伤细胞就会利用“膜纳米管”将目标细胞拉回，或是直接远程将其杀死。
研究显示，这种“远程攻击武器”可以显著增加自然杀伤细胞杀死远处目标细胞的效率，成功率达75％，而如果人为干涉切断已形成的“膜纳米管”，则成功率会降至5％。参与研究的丹尼尔·戴维斯说，如果能进一步探明这种“膜纳米管”工作的原理，将有助于研发提高人体免疫力的药物。
自然杀伤细胞是人体免疫系统对付病菌病毒的第一道防线。如果发现被感染而发生病变的细胞，自然杀伤细胞就会附着其上，传递毒素并将目标细胞杀死。(生物谷Bioon.com)
生物谷推荐原文出处：
PNAS doi: 10.1073/pnas.0910074107
Membrane nanotubes facilitate long-distance interactions between natural killer cells and target cells
Anne Chauveaua,b, Anne Auchera, Philipp Eissmanna, Eric Vivierb,c, and Daniel M. Davisa,1
Membrane nanotubes are membranous tethers that physically link cell bodies over long distances. Here, we present evidence that nanotubes allow human natural killer (NK) cells to interact functionally with target cells over long distances. Nanotubes were formed when NK cells contacted target cells and moved apart. The frequency of nanotube formation was dependent on the number of receptor/ligand interactions and increased on NK cell activation. Most importantly, NK cell nanotubes contained a submicron scale junction where proteins accumulated, including DAP10, the signaling adaptor that associates with the activating receptor NKG2D, and MHC class I chain-related protein A (MICA), a cognate ligand for NKG2D, as occurs at close intercellular synapses between NK cells and target cells. Quantitative live-cell fluorescence imaging suggested that MICA accumulated at small nanotube synapses in sufficient numbers to trigger cell activation. In addition, tyrosine-phosphorylated proteins and Vav-1 accumulated at such junctions. Functionally, nanotubes could aid the lysis of distant target cells either directly or by moving target cells along the nanotube path into close contact for lysis via a conventional immune synapse. Target cells moving along the nanotube path were commonly polarized such that their uropods faced the direction of movement. This is the opposite polarization than for normal cell migration, implying that nanotubes can specifically drive target cell movement. Finally, target cells that remained connected to an NK cell by a nanotube were frequently lysed, whereas removing the nanotube using a micromanipulator reduced lysis of these target cells.
