Interleukin-2 gene variation impairs regulatory T cell function and causes autoimmunity

Autoimmune diseases are thought to result from imbalances in normal immune physiology and regulation. Here, we show that autoimmune disease susceptibility and resistance alleles on mouse chromosome 3 (Idd3) correlate with differential expression of the key immunoregulatory cytokine interleukin-2 (IL-2). In order to test directly that an approximately twofold reduction in IL-2 underpins the Idd3-linked destabilization of immune homeostasis, we show that engineered haplodeficiency of Il2 gene expression not only reduces T cell IL-2 production by twofold but also mimics the autoimmune dysregulatory effects of the naturally occurring susceptibility alleles of Il2. Reduced IL-2 production achieved by either genetic mechanism correlates with reduced function of CD4(+) CD25(+) regulatory T cells, which are critical for maintaining immune homeostasis.     

激光化学与物理学:下一个科学新领域

原子和分子是如何与光发生相互作用的 ?人们也许会认为业已成熟的现代激光光谱学已经回答了这一基本问题 ,今后只需应用好我们的知识资源就可以了。然而 ,超短、超强脉冲激光器的发展已使人们认识到在光与物质相互作用方面尚有许多问题需要研究。众所周知 ,超短脉冲激光器使人们能够在飞秒尺度上对分子过程进行实时探测。然而最新的进展并不是出自于脉冲的超短时间宽度 ,而是起源于光脉冲的极高光强。线性调频脉冲放大器的出现 ,大大地增加了超短脉冲激光器的输出能量。现在 ,即使是在大学的实验室中也可利用实验台上的高功率线性调频脉冲放…     

Current-induced domain-wall switching in a ferromagnetic semiconductor structure

Magnetic information storage relies on external magnetic fields to encode logical bits through magnetization reversal. But because the magnetic fields needed to operate ultradense storage devices are too high to generate, magnetization reversal by electrical currents is attracting much interest as a promising alternative encoding method. Indeed, spin-polarized currents can reverse the magnetization direction of nanometre-sized metallic structures through torque; however, the high current densities of 10(7)-10(8) A cm(-2) that are at present required exceed the threshold values tolerated by the metal interconnects of integrated circuits. Encoding magnetic information in metallic systems has also been achieved by manipulating the domain walls at the boundary between regions with different magnetization directions, but the approach again requires high current densities of about 10(7) A cm(-2). Here we demonstrate that, in a ferromagnetic semiconductor structure, magnetization reversal through domain-wall switching can be induced in the absence of a magnetic field using current pulses with densities below 10(5) A cm(-2). The slow switching speed and low ferromagnetic transition temperature of our current system are impractical. But provided these problems can be addressed, magnetic reversal through electric pulses with reduced current densities could provide a route to magnetic information storage applications.