Based on whether the blood cells stick together when mixed with the antibodies, your blood type can be determined from there.
If your blood cells stick together when mixed with antibodies against type B blood, you have type B blood.
If your blood cells stick together when mixed with antibodies against type A blood, you have type A blood.
To confirm the result, the next step is reverse typing, meaning the blood sample without red blood cells -- called a serum -- is mixed with type A and type B blood cells.Type A blood will have antibodies against Type B blood in the sample and type B blood will have antibodies against Type A blood.
So, if sticking occurs when the serum is mixed with type B blood cells, you have type A blood, and if sticking occurs when the serum is mixed with type A blood cells, you have type B blood.
This is an easy -- and free -- way to determine blood type, but results are not immediate