Introduction to Hematology
The basis of these types are specific proteins called antigens that are found on the surface of red blood cells and antibodies found in the plasma.
There are four basic types:
Find out more about blood types in the population.
If we take the antibodies from the plasma of a person with type A blood (anti B antibodies) and mix them with the blood (remember...mostly red cells) of a person with type B blood, the antibodies attach themselves to the red cells and cause the red cells to clump together.
These types (and other less striking types) must be properly matched for a blood transfusion to work.