How do allergens affect the immune system?

Answer 1

your body has this thing called histamines and histamines are friendly, but if a certain allergen is affected, then histamines will start to "attack" the immune system causing a reaction or a flare-ups such as asthma, allergy,sneezing, watery eyes

Answer 2

The immune system is triggered by allergens. The allergens are irritating to the body and the immune system will try to clean or flush out the allergen with fluid, mucus, coughing and sneezing. Allergens will cause a runny nose, asthma, cough, lung wheezing and more. I hope this helps.