The ABO Blood Group System

Author: Scott A. Sheffield MS

Last update:

Introduction to the ABO Blood Group System:

Red Blood cells make (synthesize) several types of surface marker molecules. Because they can induce an immune response in a recipient of transfused blood, these molecules are also known as blood group antigens or agglutinogens.

ABO System of Antigens

Blood Type:

Unlabelled image of red blood cells
Type A blood type with A antigens
Type B blood type with B antigens
Erythrocytes without and with Type A, Type B and Type AB antigens.
Type O blood type with H antigens
The various antigens on A, B, AB, and O red blood cells.
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As well as the ABO blood group systems, 29 other blood group systems have been identified. These blood groups have names such as Rh, MNSs, Lutheran, Kell, Kidd, and Lewis.

The image descriptionchemical structures of the A, B and H antigens are very similar.

The chemical structures of the A, B, and H antigens animation slide 1
The chemical structures of the A, B, and H antigens animation slide 2
The chemical structures of the A, B, and H antigens animation slide 3
The chemical structures of the A, B, and H antigens animation slide 4
The chemical structures of the A, B, and H antigens animation slide 5
The chemical structures of the A, B, and H antigens animation slide 6
The chemical structures of the A, B, and H antigens animation slide 7
The chemical structures of the A, B, and H antigens.
  • Each is a short chain of sugars (oligosaccharide) that is typically attached to a membrane lipid
  • They differ, however, at the terminal sugar, and it’s this minor difference that establishes your blood type.
  • The ABO blood group antigens are genetically determined, and the incidence of each group varies by race.

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The Terminal Sugars of the A,B, and H antigens:

Antigen:

The chemical structures of the A, B, and H antigens animation slide 7
The N-acetylgalactoseamine terminal sugar of the A antigen
The galactose terminal sugar of the B antigen
The H antigen with no terminal sugar
The terminal sugars of the A, B, and H antigens.
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Test yourself:

The ABO blood group antigens: [image descriptionShow/image descriptionHide answers]

Test yourself image for the ABO blood group system with answers shown: N-acetylgalactoseamine, galactose, no terminal sugar, type A, type B, type AB, type O
Review the ABO blood group system and test yourself.
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