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Ex. 17 Antigen-Antibody Interactions
Part 1: Blood Typing
In this exercise you will learn how to perform a blood typing reaction. Remember when antigens from the red
blood cells encounter matching antibodies an agglutination reaction happens. This reaction causes clumps to
form as a result of the antibodies binding to the antigens on the red blood cells.
Please visit the URL below and play the blood typing game. Not only will you practice determining a patient’s
blood type, but you will also then determine which type(s) of blood the patient can receive via a blood
transfusion.
https://educationalgames.nobelprize.org/educational/medicine/bloodtypinggame/
Use the following results to determine the blood type of each patient and what blood types they are able to
accept.
Control
Blood
Type
A-
Antibody
Anti-A
Anti-B
Anti-Rh
Clumps
No Clumps
B+
No Clumps
AB+
O-
Patient
Sample
Antibody
Anti-A
Anti-B
No Clumps
1
Clumps
No Clumps
Clumps
Clumps
Clumps
2
Clumps
Clumps
No Clumps
Clumps
Clumps
Clumps
3
No Clumps
No Clumps
Clumps
No Clumps
No Clumps
No Clumps
4
Clumps
No Clumps
Clumps
Anti-Rh
Patient 1:
Patient 2:
Patient 3:
Patient 4:
Blood Type: _______
Blood Type: _______
Blood Type:________
Blood Type:________
Can accept blood
types:
__________________
__________________
Can accept blood
types:
__________________
__________________
Can accept blood
types:
__________________
__________________
Can accept blood
types:
__________________
__________________
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Use the following images to determine the blood type of each new patient and what blood types they are able
to accept.
Patient 5:
Blood Type: _______
Can accept blood types:
____________________________________
Patient 6:
Blood Type: _______
Can accept blood types:
____________________________________
Patient 7:
Blood Type: _______
Can accept blood types:
____________________________________
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Part 2: Precipitin Reaction
Precipitin reactions are another example of the product of antigen-antibody reactions. These reactions are
specific for when antibodies bind to soluble antigens and produce an insoluble precipitate. While a precipitate
will form any time these interactions occur, the maximum precipitate will always form when the antigens and
antibodies are present in equal amounts. This is known as the equivalence point and should be visible to the
naked eye.
View the results below for the precipitin reaction performed in class and then answer the questions that follow.
BSA & Water
BSA & Anti-BSA
1. Why is there no visible precipitate in the BSA & Water tube?
2. Would the precipitin reaction occur if we still used the antigen BSA but switched the antibody to Anti-Rh
(as used in the blood typing reaction)? Why or why not?