What are eosinophils ?

Eosinophils are WBCs. And they are the components of the blood .

The Normal range 1-6%(0.02-0.5 × 10^9/L)

How does it help the human body ?

1. They control mechanisms associated with allergy and asthma.
2. Help in combating multicellular parasites and certain infections 

What causes eosinophilia ?

If eosinophil count is more that 450/cu mm

Causes –

Source- textbook of pathology for dental students Ramdas Nayak , Wikipedia