Biology · Ch 15 — Body Fluids and Circulation
ABO grouping
ABO grouping
ABO grouping
The ABO system sorts blood according to the presence or absence of two surface antigens on the red blood cells, called A and B. Antigens are chemicals capable of triggering an immune response.
Matching these antigens is the plasma's own set of natural antibodies — proteins produced in response to antigens. Because of the different combinations of antigens on the RBCs and antibodies in the plasma, human blood falls into four groups: A, B, AB and O.
The way antigens and antibodies are distributed across these four groups, together with which donor groups a person of each group can safely receive from, is shown below:
| Blood group | Antigens on RBCs | Antibodies in plasma | Donor's Group |
|---|---|---|---|
| A | A | anti-B | A, O |
| B | B | anti-A | B, O |
| AB | A, B | nil | AB, A, B, O |
| O | nil | anti-A, anti-B | O |
Blood transfusion is not a matter of using any available blood: the donor's blood must be carefully matched with the recipient's beforehand, otherwise the RBCs may undergo clumping, which destroys them.
Two special cases follow from the table: …