Question

How do antibodies and antigens work together in the blood?

Answer 1

Antigens are unique signs that exist on almost every cell.
Antibodies neutralise dangers to the body, such as foreign bacteria.

Explanation:

Antigens are protein strands that are on the outside of most cells, poking out of the cell membrane or wall. They are identifiers and acts as a free pass to travel with our bodies. However they are also what antibodies bond to when they "attack" foreign bacteria.

Both are required to have a functional immune system.