# Antibody classes

Source: https://projectalevel.co.uk/biology/immunity/antibody_classes

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- There are four different antibody classes with different structures and functions.
- e.g. IgE acts in tissues and has 2 antigen binding sites and activates mast cells to release histamine. Responds to infections by larger organisms e.g. worms. But, causes response to harmless substances e.g. pollen causing hay fever (allergy).