(单词翻译:单击)
We all have that friend or coworker who insists that they never get colds because their immune system is just so strong.
我们身边都有那种朋友或同事，他们坚称因为自己强大的免疫系统，自己从不会感冒。
But research shows they might want to hold off on that boast.
但是研究表明他们可能要停止这种吹嘘。
People with more robust immune responses may actually be more likely to show symptoms of a cold.
免疫系统更强的人其实更有可能出现感冒的症状。
And that's because cold symptoms aren't caused by cold viruses, but by your body trying to show those viruses the door.
这是因为感冒的症状并不是由感冒病毒所引起的，而是因为你的身体试图让这些病毒离开。
The common cold is usually caused by a class of viruses called rhinoviruses.
普通感冒其实是由被称为鼻病毒的病毒所引起的。
Unlike many other viruses, like the flu, rhinoviruses don't damage or destroy the cells of your airway, though some do fall away.
和很多其他病毒（如流感）不同，鼻病毒不会破坏或摧毁你的呼吸道细胞，尽管有些细胞会脱落。
Instead, the symptoms you experience, like a sore throat and stuffy nose,
相反，你所经历的症状，如喉咙痛和鼻塞，
are actually caused by your own immune system responding to the virus.
其实是由你本身的免疫系统对病毒做出反应而产生的的。
Not everyone who is infected by a cold virus actually shows symptoms. In fact, about 25% of rhinovirus infections have no symptoms at all.
并不是每一个感染感冒病毒的人都会出现症状。事实上，约25%的鼻病毒感染完全没有症状。
And it's not because these people have built up immunity to those particular viruses.
这不是因为这些人已经对那些这些病毒产生了免疫力。
A 2003 study looked at healthy infants who visited the doctor either for a routine checkup or for a respiratory infection.
2003年一项研究对健康的婴儿进行了观察，这些婴儿要么去医院做常规检查，要么去医院做呼吸道感染检查。
They found that of the infants who seemed healthy and were just there for a check-up,
他们发现在那些看似健康并且只是去做检查的婴儿中，
20% of them showed evidence for a rhinovirus infection, but no symptoms.
有20%的婴儿有鼻病毒感染，但没有任何症状。
And those babies hadn't had much time to build up immunity, to colds, or anything at all, really.
这些婴儿并没有多少时间去建立对抗感冒等的免疫系统。
In people who do have cold symptoms, the severity of those symptoms often correlates with markers of inflammation.
在那些确实有感冒症状的人中，那些症状的严重程度通常与炎症相关。
These markers include cytokines: molecules secreted by immune cells that are involved in cell communication and interaction.
这些标记包括细胞因子：免疫细胞分泌的分子，参与细胞通讯和相互作用。
A cytokine called IL-8 has been shown to increase in people with viral inflammation of the nose.
一种被称为IL-8的细胞因子已被证明会增加鼻病毒炎症患者的数量。
IL-8 is involved in recruiting white blood cells to infections.
IL-8涉及招募白血球感染。
This in turn heightens your inflammatory response, resulting in pain and a stuffy, runny nose.
这反过来会增加你的炎症反应，导致疼痛和流鼻涕。
And a number of studies have shown that there are greater levels of IL-8 in people with more severe cold symptoms.
一些研究表明有更严重的感冒症状的人体内的IL-8水平更高。
In one 1998 study, volunteers were inoculated with a cold via virus-filled nose drops.
在一项1998年的研究中，志愿者通过充满病毒的滴鼻液接种感冒疫苗。
Whether or not they developed an infection was measured by flushing their noses with saline in the days after the inoculation,
他们是否被感染，需要在接种的几天后通过用盐水清洗鼻子来测量，
then checking to see if that fluid contained viruses that could infect other cells in a lab.
然后检查液体中是否含有可以感染实验室其他细胞的病毒。
People who did get an infection either showed no symptoms and no IL-8 increase, or they felt sick and their levels of IL-8 went up.
感染的人要么没有出现症状，IL-8也没有增加，要么感到恶心，IL-8水平上升。
In other studies, severity of symptoms similarly didn't seem to correspond with how many copies of the virus are present in your body.
在其他研究中，症状的严重程度似乎与你体内的病毒复制数不相符。
In fact, in a 1994 study, washing healthy subjects' noses with IL-8 was enough to induce cold-like symptoms; no virus needed!
事实上，在一项1994年的研究中，用IL-8清洗健康主体的鼻子足以引发类似感冒的症状；根本不需要病毒！
This makes it seem like the bigger your immune response, the worse your symptoms will be.
这使得似乎你的免疫反应越大，你的症状就越严重。
Taken together, the evidence suggests that people with stronger or more reactive immune systems may actually experience worse cold symptoms.
总的来看，证据表明免疫系统月强大或约活跃，感冒症状就越严重。
So the next time you find yourself sniffling and sneezing, surrounded by tissues, blame your immune system.
所以下次你发现自己流鼻涕、打喷嚏时，周围都是纸巾，这都怪你的免疫系统。
But don't be too hard on it. You probably want your body to respond to colds with a bit of zeal.
但不要对它太苛刻。你可能希望你的身体对感冒有一点热情。
It's a sign that your immune system will take invaders seriously,
这表明你的免疫系统将认真对待入侵者，
and therefore, might just help protect you better against things way more dangerous than the common cold.
因此可能仅能保护你抵御比普通感冒更危险的事情。
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