Blood Types & Transfusion

In the recipient's bloodstream

Donor red cells bring their antigens. They meet the recipient's antibodies. If the two match, the antibodies attack.

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Each round cell in the picture is a donor red cell, and the small shapes stuck to its surface are its antigens. The Y shapes drifting around it are the antibodies already in the recipient's plasma. When an antibody fits an antigen, it grabs on, the cells clump, and they burst. Switch the recipient or the donor and the picture answers the question for you.

The ABO cheat-sheet

Type	Antigen on RBC	Antibody in plasma	Can receive
A	A	anti-B	A, O
B	B	anti-A	B, O
AB	A & B	none	everyone, the universal recipient
O	none	anti-A & anti-B	O only, yet it is the universal donor

Set up the transfusion

🧍 RECIPIENT (the patient)

🩸 DONOR (the bag of blood)

Transfusion reactions

🚨 Acute Hemolytic Reaction

ABO incompatibility, and the worst one. Recipient IgM antibodies destroy donor cells within about 15 minutes. You see fever, chills, low BP, back pain, and dark urine (hemoglobinuria). It can set off DIC and acute renal failure.

Febrile Reaction

An attack on donor white cells (leukocyte incompatibility). It brings fever and chills, but no hemolysis. It is uncomfortable and not usually dangerous.

Fluid Overload

Too much volume, too fast → strain on the heart (CHF), above all in older adults.

Infection / Sepsis

Contaminated blood brings in bacteria → sepsis.