Chronically over-reactive immune systems may not, though, be an entirely bad thing.
慢性过分反应免疫系统不会像过分敏感的免疫系统，虽然它也是一个坏东西。
2
An over-reactive immune system is also the cause of allergies, where a harmless agent (such as pollen) can lead to an unnecessary immune response.
过激的免疫系统也是引起过敏的原因，本来无害的物质(如花粉)会引起不必要的免疫反应。
3
These range from the idea that clean modern living makes the immune system over-reactive to random allergens to the thought that chemicals in swimming pools are responsible.