Download A5.3.1.Transfusion - Belle Vernon Area School District

Name ___________________________________
Transfusion Confusion – 60 Informal Points
Introduction
Jane Doe is in the hospital recovering from a car crash. She needs blood, but the blood bank is extremely
low. Members of her family have offered to donate, but none of them know their blood type. Jane’s brother
Tom, sister Mary, mother Harriett, and Grandpa Ed (her mom’s father) are local and are all willing to be
tested. Jane’s other sister Sue is away at college, but she is going to have her blood tested at school and
have the results sent to the hospital. Jane’s father, John and Grandmother Mona (her mom’s mother) have
passed away. Their blood types remain unknown.
There are four types of human blood – type A, type B, type AB and type O. Only certain blood types are
compatible with one another and can be safely transferred from person to person in a transfusion. In this
activity, you will learn what controls blood type as well as what determines if your blood will “mix well” with
that of another person’s. The body has an innate need to protect itself and if something foreign is introduced,
it will attack.
Anything that is foreign to the body and gets your immune system fired up is referred to as an antigen.
Antibodies are proteins in blood and lymph that seek out and bind to specific antigens. These specialized
proteins are one of the primary defenders in your body’s army of immunity. Your body contains tons of
antibodies, each designed to target and destroy a specific antigen. Our red blood cells have antigens on their
surface that act to identify the type of cell. A person with blood type A has A antigens on his/her red blood
cells. What antigens do you think you would find on the red blood cells of a person with B blood?
Someone who has the A antigen on his/her blood cells would not have Anti-A antibodies circulating in his/her
plasma, the liquid portion of blood. If he/she did, the Anti-A antibodies would find and attack the red blood
cells marked with the A antigen. When this happens, the blood agglutinates or clumps. A person with the A
antigen does, however, have circulating anti-B antibodies. These antibodies do not attack the red blood cells
with the A antigen. But what if you introduced B blood cells into the system? In the lab, you will use the rules
of antigen/antibody interactions and the presence of visible clumping to determine blood type.
Much of this is a review of last year, but this year we are also adding in the concept of the Rh factor (Rhesus
Factor.) Rh-positive is the dominant trait whereas Rh- negative is the recessive trait. When a person is Rhpositive they have additional antigens on their red blood cells. However, the immune response is a little
different than for blood type. For example, a person with blood type O naturally has both anti-A and anti-B
antibodies in his or her blood, meaning if he or she were ever given A, B, or AB blood it will be rejected and
kill the patient. However, a person that is Rh-negative does not naturally have antibodies for the positive
antigen, instead the immune system first manufactures them only after having been exposed to the positive
antigen. For this reason a person that is Rh-negative may safely, without side effects, be given Rh-positive
blood one time. However, this initial exposure will cause the body to begin producing Anti-positive
antibodies which will last the remainder of their lives. If the person is given Rh-positive a second time then
there will be an attack and ill side effects will occur. These side effects are serious, but rarely deadly, like
being given the wrong blood type. For this reason, in an extreme emergency with extenuating
circumstances it is permissible to give an Rh-negative patient the positive blood. This is also the reason why
an Rh-negative woman pregnant with a Rh-positive baby can carry the first baby to full term without any
issue, but a second Rh-positive baby would be miscarried without medical intervention. Luckily, modern
medicine has discovered the Rh immune globulin (RhIg) that can be injected into the mother and keep both
her and her baby safe even if their blood types are not compatible.
In this activity, you will type the simulated blood of your patient as well as the blood of her family members.
You will analyze the results and use your knowledge of antigen/antibody interactions to determine who is a
potential blood donor for Jane. Accurate blood typing is essential for safe blood transfusions. Using
information from your blood typing tests, you will create a family pedigree for blood type and use information
on this genetic family tree to determine the blood type of those you could not test. As you complete this task,
you will learn about the interactions between antigens and antibodies, and you will review basic principles of
genetics and inheritance.
Procedure
Part I: Blood Typing
1. Follow your teacher’s lead to review blood basics.
There are many different ways to classify blood types, but the most common blood type classification
system is the ABO (said "A-B-O") system. There are four blood types in the ABO system: Type A, Type
B, Type AB, and Type O. These blood types refer to different versions of carbohydrate molecules
(complex sugars,) which are present on the surface of red blood cells.
People with:
Have:
Type A blood
Type A carbohydrate antigen
molecules
on their red blood cells
Type B blood
Type B carbohydrate antigen
molecules
on their red blood cells
Type AB blood
Type A and B carbohydrate
antigen molecules
on their red blood cells
Type O blood
Neither A nor B carbohydrate
antigen molecules
on their red blood cells
The Type A and Type B carbohydrate molecules are called antigens because they stimulate the body to
produce an immune response, including antibodies. This means that if you have A and/or B antigens on
your red blood cells then the immune system will NOT generate antibodies towards it and they are okay
to be in your body. However, if a person does not have the A and/or B antigens then the immune system
would attack this type of blood if it every entered the body because it would see the blood as a foreign
substance. Antibodies are special proteins that travel in the blood and help our bodies to destroy
viruses or bacteria that may have infected our bodies (see figure below.)
Normally, we do not make antibodies against any molecules that are part of our own bodies. Thus,
antibodies help to defend against invading viruses and bacteria, but normally antibodies do not attack our
own body cells. For example, people with Type A blood do not make antibodies against the Type A
antigen, which is present on their red blood cells, but they do make antibodies against the Type B
antigen. Test your understanding of blood groups by filling in the blanks in the chart.
Blood group A
If you belong to the blood group A, you have A
antigens on the surface of your red blood cells and
_______ antibodies in your blood.
Blood group B
If you belong to the blood group B, you have B
antigens on the surface of your red blood cells and
_______ antibodies in your blood.
Blood group AB
If you belong to the blood group AB, you have both A
and B antigens on the surface of your red blood cells
and no anti-A or
anti-B antibodies in your blood.
Blood group O
If you belong to the blood group O, you have neither
A nor B antigens on the surface of your red blood
cells, but you have both
______ and _____ antibodies in your blood.
Blood transfusions — who can receive blood from whom?:
If you are given a blood transfusion that does not match your blood type, antibodies present in your blood
can react with the antigens present on the donated red blood cells. For example, if a person who has
Type A blood is given a Type B blood transfusion, then this person's anti-B antibodies will react with the
Type B antigens on the donated red blood cells and cause a harmful reaction. This reaction can cause
the donated red blood cells to burst and/or clump together and block blood vessels. This type of
transfusion reaction is illustrated in the figure below.
Transfusion reactions can be fatal. To prevent this from happening, doctors test whether a person's
blood is compatible with the donated blood before they give a transfusion. A person can only be given
donated blood with red blood cells that do not have any antigen that can react with the antibodies in the
person's blood.
Test your understanding of blood groups by completing the table below.
Blood Group
Antigens on red
blood cells
Antibodies in
plasma
Can receive
blood from
Can give
blood to
A
A
B
A or O
A or AB
B
B
A
B or O
B or AB
AB
A and B
None
Anyone
AB
O
None
A and B
O
anyone
Now, let’s get a little more specific and add in Rh factors. Positive is dominant and negative is recessive.
Fill in the following chart:
Blood Phenotype
Blood Genotypes
AA++, AA+-, AO++, AO+-
A+
A-
AA--, AO--
B+
BB++, BB+-, BO++, BO +-
B-
BB--, BO-AB++, AB+-
AB+
AB-
AB--
O+
OO++, OO+OO--
O-
Which blood type would be considered a universal donor (someone who can give blood to anyone)?
Type O since it is recessive and has no antigens to be fought by the immune system, making it safe for anyone!
Which blood type would be considered a universal acceptor (someone who can take blood from anyone)?
Type AB since is it codominant and a person with type AB blood has no antibodies. Without antibodies there are no
fighter molecules to reject any blood so a person with AB blood can take anything!
What about the Rh factor? What does Rh have to do with donating and receiving?
OO-- is the absolute best blood to donate because it is recessive in both blood type as well as Rh factor meaning anyone
can safely take this blood as many times as needed without any consequences!
Genetics of Blood Types:
Your blood type is established before you are born, by specific genes inherited from your parents. You
receive one blood type gene from your mother and another from your father. These two genes determine
your blood type by causing the presence or absence of the Type A and Type B antigen molecules on the
red blood cells.
In a heterozygous AO person, which allele is dominant, A or O? Explain your reasoning.
A because it produces antigens on the blood cells whereas O does not.
Codominance refers to inheritance in which two alleles of a gene each have a different observable effect
on the phenotype of a heterozygous individual. Thus, in codominance, neither allele is recessive—both
alleles are dominant.
Which one of the genotypes shown on the last page results in a phenotype that provides clear evidence
of codominance? Give the genotype and draw a picture of a red blood cell for this genotype to illustrate
how both alleles influence blood type in this case.
AB since both alleles show up in the blood type.
Each biological parent gives one of their two ABO alleles to their child. For example, a father who has blood type
AB has the genotype AB, so he can give either an A or a B allele to a child of his. If the mother has blood type O,
her genotype must be OO, and she can only give an O allele to a child.
Father (Type AB)
A Punnett Square is a table showing the genotypes of all possible children a couple can create given their genotypes.
Below is a punnett square shows the possible genotypes for the children of these parents. Write in the blood type for
each genotype to show the possible blood types for the children of these parents.
Mother
(Type O)
O
O
A
AO
AO
B
BO
BO
Father (Type B)
Next, suppose that a mother has blood Type A and genotype AO and the father has blood Type B and genotype BO.
Draw a Punnett square to show the possible genotypes for their children. What blood phenotype would each
genotype result in.
Mother
(Type A)
A
O
B
AB
BO
O
AO
OO
2. Put your knowledge of antigen and antibody interactions to the test as you help Jane Doe find a blood
donor. Work with a partner to test the blood of each family member and determine blood type based on
agglutination.
Blood Sample
A
B
O
Rh
Blood
Genotype
Blood
Phenotype
Jane
+
-
+
AO++ or AO+- A+
Mary
+
+
+
AB++ or AB+-
AB+
Tom
-
+
-
BO--
B-
Harriett
+
-
+
AO++ or AO+- A+
Ed
-
-
-
OO--
O-
*Note: Agglutination means “clumping.” Sometimes this is apparent by particle appearing after mixing or just a
general cloudiness.
3. Starting with Jane and working one sample at a time, place two drops of simulated blood in the A and the B
wells of a clean blood typing slide.
4. Place two drops of Anti-A serum in the well labeled A.
5. Place two drops of Anti-B serum in the well labeled B.
6. Using a separate mixing stick for each well, mix the simulated blood and antiserum for approximately ten
seconds.
7. Carefully examine each well to see if the blood has clumped. If agglutination has occurred, place a “+” in
the appropriate box in the table. Remember that you will only see agglutination if a specific antibody meets
up with its specific antigen. Record your observations and use the information to determine blood type.
8. Using a fresh tray for each sample, repeat the blood typing steps to determine the blood type of the other
family members.
9. Using information from the lab, determine who is able to donate blood to Jane and list in the space below.
Note that Sue just called in to let everyone know that she is blood type O.
Part II: Genetics of Blood Type
10. Remember that pedigrees are diagrams of family relationships that illustrate how a particular trait is passed
from person to person. With your teacher, review the structure of pedigrees using the Pedigree Resource
Sheet.
11. In the space below, draw a pedigree that shows the distribution of blood type in the Doe family. Remember
that in a pedigree, men are represented by squares and women are represented as circles.
12. Write the name of the individual underneath each square or circle in the pedigree, and write the blood type
inside of the shape.
13. Work with your partner to analyze your pedigree and to determine blood type for John and Mona. You did
not test their blood, but the pedigree will give you many clues. You may be able to narrow it down to just
one blood type or you may find that there is more than one possibility. That is OK – take it as far as you
can.
Mona would have to be AO and John would have to be BO.
Conclusion Questions
1. Explain why a person who has AB blood is considered the universal recipient. Why can this person receive
any other blood type?
Type AB since is it codominant and a person with type AB blood has no antibodies. Without antibodies there are no
fighter molecules to reject any blood so a person with AB blood can take anything!
2. Explain why Jane cannot receive blood from her sister Mary.
Jane is blood type A, meaning she has Anti-B antibodies. Mary has AB blood so if Jane were to take Mary’s
blood there would be B-antigen in her body and her Anti-B antibodies would attack and kill the cells, killing
Jane.
3. What happens when an antigen on a red blood cell comes in contact with the antibody designed to seek it
out? Why would this be a bad thing?
The antibody is a fighter molecule and would attack the antigen, killing the blood cell and the person.
4. Explain how you were able to determine John’s blood type (phenotype.) What is John’s genotype?
John must have a genotype of BO and a blood type of B. We know this because his daughter Sue is type O so
she must have gotten an O allele from each of her parents. Johns daughter Mary is Type AB and had to
have gotten the A from mom which means dad must have a B to have given her.
5. Explain why blood is classified as a type of connective tissue.
Blood connects the body systems together bringing the needed oxygen, nutrients, hormones and
other signaling molecules, and removing the wastes.
6. Explain how blood type contributes to your identity.
Each person is one of four blood types, A, B, AB or O. Blood type can never change so it is part of a person’s
identity.