Blood Typing Lab
Introduction
Around 1900, Karl Landsteiner discovered that there are at least found
different kinds of human blood, determined by the presence or
absence of specific antigens (also called agglutinogens) on the surface
of the red blood cells (also called erythrocytes). These antigens are
designated as A and B. So a person who has A antigens on the red
blood cell surface would have blood type A. The absences of A or B
antigens is called blood type O.
Humans normally produce antibodies against antigens that are not on
their red blood cells. A person with A antigens (blood type A)
produces anti-B antibodies. A person with type O blood produces
both anti-A and anti-B antibodies. What antibodies would a person
with blood type AB have? ____________
So why would doctors need to know your blood type before you get a blood transfusion? If a person
who has type A blood receives a donation of type B blood, the person’s anti-B antibodies will “attack”
the donated type B blood cells. This causes agglutination or clotting and is fatal.
Look at Table 1. Fill in the missing parts of the table according to what we’ve discussed thus far.
TABLE 1: BLOOD TYPES
Antigens on red
blood cells
Blood Type
Genotypes
A
IAIA or IAi
B
IBIB or IBi
B
AB
IAIB
A&B
O
ii
Antibodies
Can donate
to…
Can receive
from…
Anti-B
A & AB
A&O
B & AB
A, B, AB, & O
Anti-A & Anti-B
A, B, AB, & O
You might be asking yourself about the positive (+) or negative (-) that always follows a blood type, i.e.
A- or AB+. The Rh factor is yet another set of antigens in human red blood cells that were discovered in
1940. The genetics of the Rh blood group is complicated because there are at least 8 alleles and six
different antigens for the Rh factor. To simplify this, one is designated Rh+ for presence of any of the Rh
antigens and Rh- for the complete absence of the antigens.
Today we will be looking at the agglutination (clotting) of the blood. There is a simple test to determine
blood type, performed with antisera containing high levels of anti-A, anti-B, or anti-Rh antibodies.
Several drops of each kind of antiserum are added to separate samples of blood. You will use Table 2 to
figure out blood types. For example, if agglutination occurs only in the sample to which anti-A was
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added, the blood type is A-. If agglutination occurs in with all three antisera, the blood is type AB+.
Agglutination with Anti-Rh serum indicates Rh+ while no agglutination means the blood is Rh-.
Use Table 2 to see if you can determine the blood types in the example in Figure 1.
TABLE 2: AGGLUTINAION REACTION OF ABO BLOOD-TYPING SERA
Agglutination or not?
BLOOD TYPE
Anti-A Serum
Anti-B Serum
Anti-Rh Serum
Yes
No
No
AYes
No
Yes
A+
No
Yes
No
BNo
Yes
Yes
B+
Yes
Yes
No
ABYes
Yes
Yes
AB+
No
No
No
ONo
No
Yes
O+
Remember: THEY ARE WHAT THEY CLOT!
What blood type is shown in the results pictured?
Now you are ready to complete some blood typing! Get the following materials at the front of
the room before moving on:
MATERIALS NEEDED PER GROUP
SHARED MATERIALS
4 pieces of stained cloth squares
6 blood typing trays
18 toothpicks
1 Vial – Victim’s Blood
1 Vial – Suspect #1
1 Vial – Suspect #2
1 Vial – Suspect #3
1 Vial – Suspect #4
1 Vial – anti-A serum
1 Vial – anti-B serum
1 Vial – anti-Rh serum
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SCENARIO
Crime investigators were called to the scene of a burglary. Mr. Smith
had come home, only to find someone robbing his apartment. As the
criminal rushed to the leave the apartment, he ran into a glass door,
cutting his arm. The blood samples from the crime scene, along with
the victim’s blood, were sent to the forensic lab to be analyzed. After
the crime investigations carefully reviewed all of the available
evidence, they apprehended four suspects. The last remaining piece
of evidence needed to solve the crime is to match the blood type
found at the scene of the crime with one of the suspects. You, along with your classmates, have been
chosen to provide this last piece of evidence and determine which of the suspects the burglar is.
PROCEDURE
You will determine the blood type of the victim, the four suspects, and the blood found at the scene of
the crime.
1. Use a marker to label each of your six blood typing trays as follows:
Tray # 1: Crime Scene
Tray #2: Victim
Tray #3: Suspect #1
Tray #4: Suspect #2
Tray #5: Suspect #3
Tray #6: Suspect #4
2. To determine the blood type found at the crime scene, place 3-4 drops of blood (on the teacher
demo desk) in each of the A, B, and Rh wells of the blood typing Tray #1 labeled “Crime scene.”
3. Place 3-4 drops of the simulated anti-A serum on the blood in the A well of the tray.
4. Place 3-4 drops of the simulated anti-B serum on the blood in the B well of the tray.
5. Place 3-4 drops of the simulated anti-Rh serum on the blood in the Rh well of the tray.
6. Obtain three toothpicks. Stir each sample of anti-serum and blood with a separate clean toothpick
for 30 seconds (do not cross-contaminate toothpicks). To avoid splattering the simulated blood, do
not press too hard on the typing tray.
7. Observe the slide and record your observations in Table 3 of the Analysis section. To confirm
agglutination (clotting) try reading text through the mixed sample. If you cannot read the text,
assume you have a positive reaction. See image below.
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(Positive)
(Negative)
Once you’ve determine the blood type found at the scene of the crime, you will then type the victim and
the four suspects.
8. Place 3-4 drops of the victim’s blood in each of the A, B, and Rh wells of Tray #2: Victim.
9. Place 3-4 drops of the Suspect #1’s blood in each of the A, B, and Rh wells of Tray #3: Suspect #1.
10. Place 3-4 drops of the Suspect #2’s blood in each of the A, B, and Rh wells of Tray #4: Suspect #2.
11. Place 3-4 drops of the Suspect #3’s blood in each of the A, B, and Rh wells of Tray #5: Suspect #3.
12. Place 3-4 drops of the Suspect #4’s blood in each of the A, B, and Rh wells of Tray #6: Suspect #4.
13. Place 3-4 drops of the simulated anti-A serum in each A well on the five trays.
14. Place 3-4 drops of the simulated anti-B serum in each B well on the five trays.
15. Place 3-4 drops of the simulated anti-Rh serum in each Rh well on the five trays.
16. Stir each sample with a SEPARATE clean toothpick for 30 seconds.
17. Observe and record you results in Table 3; write “yes” if it clots (you cannot read text underneath)
and “no” if there is no clot (you can read text underneath).
ANALYSIS
TABLE 3: AGGLUTINATION REACTIONS
Blood Source
Anti-A reaction
Anti-B reaction
Crime Scene
Victim
Suspect #1
Suspect #2
Suspect #3
Suspect #4
APPLICATION
1. Who did you find matched the blood at the crime scene?
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Anti-Rh reaction
Blood Type
2. As a forensics technician, the courts have asked you to summarize your finds to the jury. Explain what
you would say in the space below (remember, it is your job to report the facts, not decide who is
guilty).
3.
a. Circle one of the following suspects:
Suspect #1
Suspect #2
Suspect #3
Suspect #4
b. Using the information from Table 1 and the data from your blood type analysis, what ABO
antigens are present on the suspect’s red blood cells? _____________________________________
c. What ABO antibodies are found in the suspect’s blood ? _________________________________
d. What is the suspect’s blood type? ____________________________________________________
e. If the suspect needed a blood transfusion, what blood type(s) could he/she receive?
______________________________
f. What blood types could safely receive this suspect’s blood? _______________________________
4. How are antibodies like security guards? Could this be a bad thing?
5. Why is it necessary to match a donor’s and recipient’s blood before a transfusion?
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6. Blood typing is a beneficial way to gather evidence at a crime scene. Describe at least two other ways
blood typing can be beneficial to people.
7. How can what you learned today be applied to your life? Also, why would it be important for you to
know your blood type?
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