Aperson who has allergies has a compromised immune system because the body’s immune system:

The body's immune system thinks what he/she is eating or inhaling is a pathogen.  The immune system sends white blood cells to attack.  This triggers an allergic reaction.
For example: I am allergic to asparagus (I'm not joking, I really am) and walnuts.  Anytime I eat one of those, my body's immune system thinks it's a pathogen for some reason and attacks and triggers an allergic reaction in me.  This makes my breathing hard and makes it really itchy.  Good thing it's not that severe so I can eat some if I want, but sometimes allergic reactions could cause hospitalization or death.

She should ice it and put ointment on it. thats what my momma does.

  eukaryotic cells may arise from sexual reproductions, resulting in more genetic variation  i would say that is the answer