Blood Groups and Safe Transfusion
Who can give to whom, and why.
Karl Landsteiner found that the proteins on a red cell decide who may receive it. Match each card to the fact that goes with it.
Free play — tap an item on the left, then its partner on the right; each link tells you why. Switch to when you're ready to test yourself.
What this lesson covers
Challenges to clear
- Match every card to its fact.
- Connect the Rh negative mother with an Rh positive husband to what happens to her children.
The task
Karl Landsteiner found that the proteins on a red cell decide who may receive it. Match each card to the fact that goes with it.
What this lesson covers
- Group A — Antigen A on the red cells, antibody B in the plasma (The rule is always the opposite pair: whichever antigen you carry, you carry the antibody against the other one. If you carried the matching antibody you would clump your own blood.)
- Group B — Antigen B on the red cells, antibody A in the plasma (Same opposite rule. This is why B blood entering an A patient meets antibody B and clumps at once.)
- Group AB — Both antigens present, no antibodies at all (With no antibodies in the plasma there is nothing to attack incoming red cells, so AB is the universal recipient.)
- Group O — No antigen at all, but both antibody A and antibody B (With no antigen on its red cells there is nothing for anyone else's antibodies to attack, so O is the universal donor.)
- A patient of group A may safely receive — Blood from A and O only (The patient's own antibody B destroys anything carrying antigen B, which rules out B and AB donors.)
- A patient of group B may safely receive — Blood from B and O only (Antibody A in the patient's plasma rules out A and AB donors. Mirror image of the group A case.)
- A donor of group AB may give to — Group AB patients only (AB red cells carry both antigens, so every other group has an antibody waiting for them. Universal recipient and universal donor are opposite ends of the same logic.)
- Rh positive blood — D antigens are present on the red cell surface (Rh negative blood lacks them. The factor is named after the rhesus monkey, in which it was first found.)
- An Rh negative person given Rh positive blood twice — The second transfusion reacts and can prove fatal (The first transfusion sensitises the recipient, who makes an anti-Rh antibody within about two weeks. The second one meets that antibody. It behaves rather like an allergy.)
- An Rh negative mother with an Rh positive husband — The first child is normal but a second may be harmed (The first Rh positive foetus sensitises the mother. If a second Rh positive child is conceived soon after, her antibodies can attack it, sometimes causing death of the foetus and abortion.)
Hint
Antigens sit on the red cell; antibodies float in the plasma. Ask one question only: does the recipient carry an antibody against the donor's antigen? O has no antigen so nobody attacks it — universal donor. AB has no antibody so it attacks nothing — universal recipient. Trap: universal donor and universal recipient are not the same group, and O can receive only from O.