Simulated Blood Typing Activity
(adapted from Ward's simulated blood kit and http://www.waksmanfoundation.org/labs/rochester/blood.htm)
Around 1900 it was discovered that there are at least 4 different kinds of human blood. This is based on the fact that on the surface of the red blood cells there may be one or more proteins, called antigens. These antigens are called A and B. Antibodies are produced in the blood plasma against these A and B antigens, and continue to be produced throughout a personís life.
A person normally produces antibodies against the antigens that are not present on his or her red blood cells. For example, a person with antigen A on his red blood cells will produce anti-B antibodies; a person with antigen B will produce anti-A antibodies; a person with neither A or B antigens will produce both anti-A and anti-B antibodies; and, a person with both antigens A and B will not produce these antibodies.
The 4 blood types are known as A, B, AB and O. Blood type O (persons with neither A or B antigens) is the most common in the United States (45% of the population). Type A is found in 39% of the population. Type B is 12% of the population, and type AB is found in only 4% of the population.
For the purposes of Rh incompatibility the Rh (Rhesus) blood group system operates as a one gene - two allele system. The gene product is identified as the RhD antigen or D antigen. The protein product of the gene is a transmembrane protein composed of over 400 amino acids.
|Rr||R or r|
If a mother who is Rh negative
(rr) is carrying a fetus who is Rh positive (Rr, must be a
heterozygote), the mother has the capacity to produce immune antibodies to the
Rh antigens on the fetal RBC. Fortunately, the mother's immune system does not
come into contact with the fetal RBC until the time of birth when the placenta
ruptures and some of the fetal RBC enter the mother's blood stream.
So, the mother will make antibodies to the Rh antigens on the fetal RBC but the fetus has been born so it does not encounter mother's antibodies. However, the next Rh positive fetus will be at risk since the mother will retain a low level of circulating antibodies against the Rh antigen. This may lead to the death of fetal RBC late in the pregnancy when the mother loads the fetus with a sampling of her antibodies in a process known as "passive immunity".
But, if the mother's immune system is kept from seeing the fetal RBC, she will never make antibodies to the Rh angtigens. This can be accomplished by giving the new mother an injection of antibodies (made by someone else) directed against the Rh antigens on the fetal RBC. The injected anti-Rh antibodies react with the fetal RBC and the mother's immune system removes the antibody-antigen complex without recognizing the foreign Rh angtigen.
The naturally occuring ABO incompatibility system operates in a similar manner and accounts for the lower than expected frequency of Rh incompatibile births. An ABO incompatible mating is one in which the mother has serum antibodies (anti-A or anti-B or both) directed against the antigens on the RBC of the fetus. Thus, an O-type mother who is Rh negative would have both anti-A and anti-B antibodies in her serum. If her fetus was A or B and Rh positive, her anti-A and anti-B antibodies would clear the fetal RBC and she would not have a chance to make antibodies against the Rh antigens on the fetal RBC.
Because of the different blood types, certain blood groups can only give or receive blood from other specific blood groups:
|Blood Type||Antigens on Blood Cells||Antibodies in Plasma||Can Give Blood to||Can Receive Blood from|
|A||A||anti-B||A or AB||O or A|
|B||B||anti-A||B or AB||O or B|
|AB||A and B||none||AB||O, A, B, AB|
|O||none||anti-A &-B||O, A, B, AB O|
If blood cells are mixed with antibodies the cells will clump together. This is called agglutination. This is why it can be very dangerous if you receive the wrong blood type in a transfusion.
Blood typing is performed by mixing a small sample of blood with anti-A or anti-B antibodies (called antiserum), and the presence or absence of clumping is determined for each type of antiserum used. If clumping occurs with only anti-A serum, then the blood type is A. If clumping occurs only with anti-B serum, then the blood type is B. Clumping with both antiserums indicates that the blood type is AB. No clumping with either serum indicates that you have blood type O. Here are some examples:
|Anti-A Serum||Anti-B Serum||Anti-Rh Serum||Blood Type|
|Clumps||No Clumps||Clumps||Type A+|
|No Clumps||Clumps||Clumps||Type B+|
|No Clumps||No Clumps||No Clumps||Type O-|
A personís blood type is inherited from their parents, just like any other genetic trait. Persons with blood type A have inherited one or two copies of the gene for the A antigen, one from each parent. Persons with blood type B have inherited one or two copies of the gene for the B antigen. Persons with blood type AB have inherited on copy of the A antigen from one parent and one copy of the B antigen gene from the other parent. Persons with blood type O inherited neither A nor B genes from their parents.
Blood typing can be used in legal situations involving identification or disputed paternity. In paternity cases a comparison of the blood types of mother, child, and alleged father may be used to exclude a man as the possible parent of a child. For example, a child with the blood type AB whose mother is type A could not have a father whose blood type is A or O. The father must have blood type B.
NOTE: We are using simulated blood for this activity.
Materials Needed per team of 2 students (use Wardís simulated blood typing kit)
4 blood typing slides
4 unknown "blood" samples (Mr. Smith, Ms. Jones, Mr. Green, Ms. Brown)
anti-A, anti-B anti-serums and Anti-Rh antiserum
slide #1: Mr. Smith
slide #2: Ms. Jones
slide #3: Mr. Green
slide #4: Ms. Brown
9. Do any of the wells clump (agglutinate) or not? (it will look a little like light strawberry jam) Record your observations and results in your journal. What are the blood types of each of the 4 samples?
|Anti-A Serum||Anti-B Serum||Anti-Rh serum||Observations Blood Type|
|Slide #1: Mr. Smith|
|Slide #2: Ms. Jones|
|Slide #3: Mr. Green|
|Slide #4: Ms. Brown|
Post Lab Questions:
1. What ABORh agglutinogens are present on the RBC of Mr. Green's blood?
2. What ABORh agglutinins (antibodies) are present in the plasma of Mr. Green's blood?
3. If Ms. Jones needed a transfusion, what ABORh type(s) of blood could she safely receive?
4. If Ms. Brown were serving a donor, what ABORh blood type(s) could receive her blood safely?
5. Why is it necessary to match the donor's and the recipient's blood before a transfusion is given?
6. What happens to red blood cells that are agglutinated?
7. What is the difference between agglutinogen and agglutinin?
8. Explain the basis of the ABO and Rh blood types.
9. Could a man with an AB+ blood type be the father of an O- child? Why or why not?
10. Could a Type B- child with a Type A- mother have a Type A+ father? A type AB father? Explain.