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Blood Typing Lab Test Simulation

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Introduction

The blood typing test determines what surface antigens are present on an individual’s erythrocytes (RBCs). Researchers have thus far identified more than 50 RBC surface antigens. They can be carbohydrates or proteins in structure and have designated names or abbreviations such as ABO, Rh, Kell, Duffy, Kidd, and Lewis. The ABO and Rh blood groups are clinically significant because they may cause the most harm if transfused into an incompatible recipient.

ABO Blood Group Antigens

Although the ABO blood group name consists of three letters, there are only two antigens involved, called A and B. The antigen(s) that appear on the surface of an individual’s RBCs determine their ABO blood type.

  • A type: A antigen only.
  • B type: B antigen only.
  • AB type: both A and B antigens.
  • O type: neither A nor B antigens.

ABO Antigens Structure

ABO Blood Group Inheritance

Anti-A and Anti-B Antibodies

Rh Blood Group Antigens

Another RBC surface antigen group, the Rh group, can also cause great harm. Researchers applied the Rh designation after discovering the antigen group in rhesus macaque primates. 

Rh Antigen Structure

Rh Antigen Inheritance

Anti-Rh Antibodies

Rh Sensitization

ABO Transfusion Protocols

It is best to transfuse only matching blood types. For example, a blood type B+ recipient should only receive RBCs from a blood type B+ donor. However, when acute hemorrhage threatens a person’s life, there may not be time for proper crossmatching of blood types. In this case, RBCs from a donor with blood type O− blood can be transfused. Type O RBCs do not display A or B antigens, so the anti-A or anti-B antibodies in the recipient’s blood will not encounter any RBC surface antigens on the donated RBCs, and agglutination will not occur. For this reason, individuals with type O- blood are often called universal donors.

There is a potential problem with the universal donor designation. If an Rh− recipient had prior exposure to the Rh antigen, antibodies for this antigen would likely be present in the recipient’s blood and trigger agglutination to some degree. 

Recipients with blood type AB+ are known as the universal recipients. They can theoretically receive RBCs of any blood type because they do not produce anti-A, anti-B, or anti-Rh antibodies.

Subject Information

Personal and Medical Histories

The subjects for this exercise are husband and wife and soon-to-be parents.

The birth of the child will be the first for both parents.

The couple wants to determine if their different blood types could cause any potential harm to the fetus or future offspring.

Blood typing lab test case subjects

Test Procedures

Prepare Slide

Partition a glass slide into three sections using a marking pen and label them as “A,” “B,” and “D.”

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Lance Finger

Use a lancet device to pierce the skin of the index finger.

Allow a large drop of blood to accumulate on the finger surface.

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Transfer Blood to Slide

Place a drop of blood in each labeled area by gently touching the slide with the lanced finger.

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Add Antisera to Blood

Add a small drop of anti-A serum to the first blood sample, anti-B serum to the second sample, and anti-D (Rh) to the third sample.

The anti-A and anti-B antisera contain IgM monoclonal antibodies, and the anti-D antiserum typically contains a mixture of IgG and IgM monoclonal antibodies.

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Mix Antisera and Blood

Stir the antisera and blood using a different stir stick for each sample.

This will increase the contact between antigens and antibodies and accelerate the agglutination reactions.

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Place Slide on Viewing Box

Move the blood samples to a heated viewing box. Gently rock the viewing box to continue mixing the blood samples and antisera.

If red blood cell surface antigens are present, the heat the box produces will accelerate the agglutination reactions, which occur within a few minutes (in real time).

A positive Rh reaction typically takes longer and is less pronounced because the antibodies in the antiserum are smaller (IgG) than those (IgM) found in the anti-A and anti-B sera.

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Test Results

Husband’s Results

Continue rocking the viewing box, then examine the husband’s blood samples for agglutination.

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Wife’s Results

Continue rocking the viewing box, then examine the wife’s blood samples for agglutination.

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Assessment

ABO Blood Group Questions.
What is the husband’s blood type?

O +

What ABO alleles could he possibly have?

OO alleles

What is the wife’s blood type?

A –

What ABO alleles could she possibly have?

AA or AO alleles

What ABO alleles could their child inherit?

AO or OO

What is or are the child’s possible ABO blood type(s)?

A or O

What possible ABO antibodies will the child start producing after its birth.

If it is blood type A, it will make anti-B antibodies. If it is blood type O, it will make both anti-A and anti-B antibodies.

Rh Blood Group Questions.
What are the parent’s Rh types?

The husband is Rh+ and the wife is Rh-.

Is it likely that either parent would have anti-Rh antibodies in their blood?

No. the husband is Rh+ and would not produce antibodies to his own blood type. The wife, who is Rh-. would not produce anti-Rh antibodies except if she is exposed (sensitized) to incompatible Rh+ blood.

How do Rh surface antigens differ in structure from ABO surface antigens?

Rh antigens are transmembrane proteins and ABO antigens are oligosaccharides.

Which RH antigen is most clinically significant?

D

How do anti-Rh antibodies compare in structure with anti-A and anti-B antibodies?

Anti-Rh antibodies are much smaller (two antigen-binding sites) than ABO antibodies (10 antigen-binding sites).

Are most people in the United States Rh+ or Rh-?

Rh+, because the Rh+ allele is dominant.

Is the child likely to be blood type Rh+ or Rh-?

Rh+, because the Rh+ allele is dominant.

Will the wife produce anti-Rh antibodies that are harmful to the blood of the current fetus?

Not likely because fetal Rh+ cells rarely cross the placenta during pregnancy.

What is Rho-GAM?

Rho-GAM (Rhₒ(D) immune globulin) is an injection of anti-D antibodies.

When would Rho-GAM be given to the wife?

The injection should be administered to the wife shortly after the baby’s birth.

How would Rho-GAM affect the wife’s immune system?

The wife may become exposed to the baby’s Rh+ cells during or immediately after birth. The injection would eliminate any fetal RBCs before they are recognized, and the wife’s immune system starts producing anti-Rh antibodies.

How does Rho-GAM help prevent problems with the wife’s future pregnancies?

If Rho-GAM is not administered, the wife’s immune system may produce anti-Rh antibodies. These IgG antibodies are relatively small and can cross the placenta and enter the bloodstream of a future fetus. The anti-Rh antibodies would destroy the fetal RBCs, causing a condition is known as hemolytic disease of the newborn (HDN) or erythroblastosis fetalis.

Donor/Recipient Questions.
To which blood type(s) can the husband safely donate blood?

He can donate to individuals who are A+, B+, O+, or AB+.

Explain your previous answer.

The husband is type-O, so his RBCs lack A and B antigens. If he gives blood to type-A or type-B individuals, the naturally occurring anti-A and anti-B antibodies in their plasma cannot bind to the husband’s type-O RBCs. The plasma of type-AB individuals do not contain anti-A or anti-B antibodies.

Also, the husband should not donate to individuals who are Rh- because they could develop anti-Rh antibodies, which could cause problems with future donations.

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References and Attributions

References

National Library of Medicine (NIH) – Blood Typing

U.S. Food and Drug Administration – Blood Grouping Reagents

Attributions

OpenStax, Anatomy, and Physiology

Access for free athttps://openstax.org/books/anatomy-and-physiology/pages/1-introduction

Reference page: “Blood Typing