ABO Blood Group
SWBIC Educational Resources
Activities & Materials
ABO Blood Group
Human red blood cells contain protein molecules in their cell membranes.
These particular proteins are called "antigens" and determine the blood type
of an individual. There are three kinds of antigens that may be used on human
red blood cells: an antigen named "A", an antigen named "B", and an antigen
All of the red blood cells in a single individual contain the same antigens.
A person whose red blood cells have the "A antigen" has the
blood type A. People whose red blood cells have the
"B antigen" have the blood type B. Some people have
red blood cells that contain both "A and B antigens" so they have the
blood type AB. Other people have red blood cells
with "neither A nor B antigens" so they have the blood type
The other antigen, Rh, is present in some people and absent in others. The
"Rh factor" may be found along with the A and/or B antigens. People with
the Rh antigens are distinguished with a "+" in their blood type, and those
without the Rh antigen have a "-" in their blood type.
antigen A and the Rh antigen
antigen B and the Rh antigen
antigen A, antigen B and the Rh antigen
antigen A and antigen B
no antigen present on the red blood cells
ACTIVITY to practice "Typing Blood": On the
attached sheet, identify and label the red blood cells according to the type t
The type of antigens on the red blood cells is only part of the story. The
other part of the story is about "antibodies". Antibodies are "Y-shaped"
proteins produced by the individual's immune system to protect against foreign
antigens. Whatever antigens are not produced by an individual are recognized
as foreign and are sought out and bound by antibodies.
For example, people with Blood Type A+ carry the A antigen and the Rh antigen,
and produce antibodies against the B antigen. Those with Blood Type B- carry
the B antigen, and produce antibodies against the A antigen and the Rh antigen.
People who have the blood type AB- produce antibodies against
Those with blood type O+ produce antibodies against
What antibodies does someone with the B+ Blood Type produce?
ACTIVITY to practice production of antibodies against foreign red blood
cell antigens: On the attached "ANTIBODY"
sheet,(1) identify each of the antibodies in terms of the antigen it
binds, and (2) identify the blood type(s) of the people who produce each of
the specific antibodies.
So, why is this antigen-antibody stuff important to anyone? It is primarily
important for a person receiving a blood transfusion (and the people who
love them). The binding of antibodies to antigen causes at least two serious
problems. First, the tails on the "Y-shaped" antibodies become tangled up
causing "clumps" of red blood cells with the antibodies, the red blood cells
can no longer pick up or deliver oxygen, and they could block blood vessels.
The second problem caused by antibody-antigen binding is that the cells that
are bound are marked for destruction and will be killed shortly after being
Developed for SWBIC by Arlene Antilla, Ph.D, Northern New Mexico Community