how does hayfever enter our body and what does it do inside of us?

Question: how does hayfever enter our body and what does it do inside of us?

Asked by benm to Michael on 24 Jun 2010 in Categories: General.
- Michael Loughlin answered on 24 Jun 2010:
  
  well hayfever is the immune repose to pollen..So its gets in through breathing and then effects cells in the nose lungs and so on.
  
  Its a hypersensitivity response where the body reacts aggressively against a foreign item that actually causes us no harm if left alone.
  http://www.nhs.uk/conditions/hay-fever/Pages/Introduction.aspx
  that webpage looks at symptoms and so on

Question: how does hayfever enter our body and what does it do inside of us?