复数： allergens

Your body may have a threshold for a particular allergen , such as pollen or animal dander .

人身体内对过敏原都有一个特定的界限，比如花粉或动物的皮屑。

In many cases , asthma is triggered by exposure to an allergen in the environment ( allergy-induced asthma ) .

在许多病例，哮喘是由于暴露于过敏原而触发的（过敏性哮喘）。

With food , he says , there 's often little consensus about what , exactly , the offending allergen is .

他说，就食品而言，到底什么样的过敏原达到对人有害的程度，人们几乎还没有达到共识。

The placebo , identical except that it contains no allergen , is administered in the same way but on a different day .

安慰剂是同样的甜食，只是不含过敏原，其执行方法一样，不过不在同一天。

Allergies are caused by an overactive immune system responding to an allergen such as pollen , mold , dust or pet dander .

过敏是在接触到了类似于花粉、霉菌、灰尘或者宠物毛屑等过敏原的时候免疫系统作出的过激反应造成的。