The allergen in jackfruit does not sensitize the immune system, but once birch pollen has done so, the immune system may react to jackfruit too.
菠萝蜜中的过敏原不会使免疫系统敏感，但是一旦桦树花粉刺激了免疫系统，免疫系统也会对菠萝蜜有反应。
Birch pollen, one of the most common causes of hay fever in Britain.
在英国，桦树花粉是花粉症的最常见诱因之一。
This is because the protein found in birch pollen to which people are allergic is very similar to proteins found in the flesh of apples.
这是因为在引起人们过敏的白桦树花粉中找到的蛋白质和在苹果果肉中发现的很类似。
Dr Field’s team set about the task by analysing ancient records of birch pollen preserved in lake sediments from known mammoth breeding grounds like Siberia.
菲尔德博士的研究团队已经开始这项工作，在诸如西伯利亚等己知猛犸象的繁殖地点，他们对湖区沉淀物中保存的桦树花粉的远古信息进行了分析。
Dr Field's team set about the task by analysing ancient records of birch pollen preserved in lake sediments from known mammoth breeding grounds like Siberia.
菲尔德博士的研究团队已经开始这项工作，在诸如西伯利亚等己知猛犸象的繁殖地点，他们对湖区沉淀物中保存的桦树花粉的远古信息进行了分析。
This also explains why some migrants from east Asia to northern Europe suddenly develop an allergic reaction to jackfruit once they have come into contact with birch pollen.
这也解释了为什么来自东亚的某些移民，到了北欧后，一旦接触到桦树花粉，会突然出现菠萝蜜过敏反应的现象。
This also explains why some migrants from east Asia to northern Europe suddenly develop an allergic reaction to jackfruit once they have come into contact with birch pollen .
这也解释了为什么来自东亚的某些移民，到了北欧后，一旦接触到桦树花粉，会突然出现菠萝蜜过敏反应的现象。
Significantly, this line marks the southern limit of the birch tree, a plant whose pollen is one of the causes of hay fever in northern Europe.
值得注意的是，这条线标志着桦树的南部界限，而桦树的花粉是引发北欧花粉热的一个原因。
Birch trees release their pollen between March and May, and hay fever sufferers are likely to experience the worst symptoms during April.
桦树在三月到五月之间释放花粉，因此花粉症患者在四月份可能出现最严重的症状。
Birch trees release their pollen between March and May, and hay fever sufferers are likely to experience the worst symptoms during April.
桦树在三月到五月之间释放花粉，因此花粉症患者在四月份可能出现最严重的症状。
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