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【medical-news】不要对抗发烧
Don't Fight the Fever
By Jocelyn Kaiser
ScienceNOW Daily News
7 November 2006
Nobody likes coming down with a fever, but feeling hot may do a body good. Researchers report online 5 November in Nature Immunology that a fever in mice revs up the immune response by helping white blood cells enter lymph nodes, where they join the battle against microbial invaders.
All mammals can develop fever when they're sick enough, and even cold-blooded animals with infections, such as fish and lizards, will seek warmth to raise their body temperatures. This suggests that fever somehow helps the body conquer the bugs. Immunologist Sharon Evans of Roswell Park Cancer Institute in Buffalo, New York, and coworkers are studying how fever affects the movement of white blood cells, or lymphocytes, from the blood into lymphoid tissue, where they learn to recognize and fight pathogens. Lymphocytes constantly circulate through blood vessels within lymph nodes and other lymphoid organs, but only some actually enter lymphoid tissue by crossing the walls of the vessels, known as high endothelial venules (HEVs).
Fever increases blood flow, which means more lymphocytes flow through lymphoid tissues. Evans' team had previously shown that fever also assists the passage of lymphocytes into lymphoid tissue, but they hadn't figured out what was happening on a molecular level.
So Evans and collaborators at Harvard University and in Germany gave healthy mice artificial fevers. The researchers put the mice in a warm chamber for 6 hours, which raised their core temperature 2.7 C degrees above normal, to 39.5 C (about 103 F). Then they injected the mice with lymphocytes labeled with a fluorescent dye. When viewed under a microscope, the warmed mice had more lymphocytes sticking to their HEV cells. As a result, twice as many lymphocytes as normal passed into the lymphoid tissue. The explanation: Heat caused the HEV cells to express on their surface higher levels of two so-called "homing" molecules, ICAM-1 and CCL21, which make lymphocytes tightly adhere to the HEV cells.
The new study "adds to our knowledge about why fever might be beneficial," says immunologist Andrew Luster of Harvard Medical School in Boston, who wrote an accompanying commentary. He says the findings could lead to new drugs for boosting the immune response against infections and cancer and for dampening inflammation in autoimmune diseases such as arthritis.
So what to do when fever strikes? That depends, says Evans. While fever might provide some benefit, it can be dangerous in children, and parents should follow a doctor's advice, she says. 不必抗争或畏惧发烧
没有人愿意因感冒发烧而躺倒,但感觉身体发热本身也许对身体无害。研究人员在11月5日”自然”-免疫杂志的网上报道说,发烧使小鼠的免疫反应增强,帮助白细胞进入淋巴结、在那儿参与抗击微生物等外来”侵略者”。所有哺乳动物在它们生病不轻时都会有发烧反应,甚至冷血动物如鱼、蜥蜴, 受感染时也会设法提高它们的体温. 这表明身体发烧升温有助于征服除细菌和病毒感染.免疫学家沙龙埃文斯和他在纽约布法罗罗兹韦尔癌症研究所的同事们正在研究发烧如何影响白细胞或淋巴细胞的运动、白细胞如何从血液进入淋巴组织,在那里学会识别并扑灭病原。淋巴细胞通过淋巴结等淋巴器官在血管内不断循环、但实际上只有一部分穿过血管壁（被称为高内皮静脉-HEV），进入淋巴组织的.发烧使血流增速,这意味着更多的淋巴细胞流经淋巴组织.埃文斯的研究小组的研究表明：发烧还协助淋巴细胞进入淋巴组织,但他们没有搞清在分子水平的作用机理论。
所以埃文斯和其在哈佛大学和德国的合作者们设法是健康的小鼠人为发热.他们把小鼠放在热温箱中6小时，控制箱内温度在高于正常体温2.7度，即39.5度，(约103华氏).然后注入小鼠淋巴细胞荧光标记染料.在显微镜下看,研究人员在升温环境下的小鼠体内观测到有更多的淋巴细胞坚守粘附在他们的HEV细胞.与常温下小鼠相比，有两倍量的淋巴细胞进入淋巴组织.这说明: 热引起HEV细胞在其表面高水平表达两种名谓的"巢"分子的物质ICAM-1和ccl21,这些分子是淋巴细胞紧粘HEV细胞. 新的研究显然丰富了我们有关“为什么发烧可能有益的"的知识。哈佛大学医学院的免疫学家Andrew Luster写的随文评论中表示.这些发现和结果可能导致研制新的药物，用于刺激免疫反应对付感染，癌症，抑制炎症和自身免疫性疾病,如关节炎.所以发烧时我们究竟应该干什么？这就要看具体情况而定。埃文斯说.”虽然发烧可能对身体有一些好处,但对儿童还是有危险的（持续高烧会伤害大脑）,父母应该遵循医生的忠告。“
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作者:admin@医学,生命科学 2011-07-14 11:20
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