blood types review ch.18

What determines blood type compatibility?

Interactions between plasma proteins and erythrocytes.

Who discovered blood types A, B, and O?

Karl Landsteiner discovered them in 1900.

When was blood type AB discovered?

It was discovered after A, B, and O.

What are antigens?

Complex molecules such as proteins, glycoproteins, and glycolipids that are unique to each individual.

What happens when the body detects a foreign antigen?

It produces an immune response, including the release of antibodies.

What are antibodies?

Proteins called gamma globulins that bind to antigens and help destroy them.

What is agglutination?

The clumping of cells caused when antibodies bind to antigens.

What are agglutinogens?

Antigens on the surfaces of red blood cells that determine blood type.

What are agglutinins?

Antibodies in the blood plasma that can react with RBC antigens.

What happens during a mismatched blood transfusion?

Antibodies can bind to foreign RBC antigens and cause the RBCs to agglutinate.

What are the four ABO blood types?

A, B, AB, and O.

What determines a person’s ABO blood type?

The inherited presence or absence of A and B antigens on RBCs.

When do ABO antibodies begin appearing?

About 2 to 8 months after birth.

When do ABO antibodies reach their maximum concentration?

Between about 8 and 10 years of age.

What does anti-A react against?

Antigen A.

Where is anti-A found?

In the plasma of people with type O or type B blood.

What does anti-B react against?

Antigen B.

Where is anti-B found?

In the plasma of people with type O or type A blood.

What is found on type A RBCs?

A antigens.

What antibodies are found in type A plasma?

Anti-B antibodies.

What is found on type B RBCs?

B antigens.

What antibodies are found in type B plasma?

Anti-A antibodies.

What is found on type AB RBCs?

Both A and B antigens.

What antibodies are found in type AB plasma?

Neither anti-A nor anti-B.

What is found on type O RBCs?

Neither A nor B antigens.

What antibodies are found in type O plasma?

Both anti-A and anti-B.

How can ABO blood type be determined?

By placing blood in anti-A serum and anti-B serum and observing whether agglutination occurs.

What happens when type AB blood is placed in anti-A and anti-B sera?

It agglutinates in both.

What happens when type O blood is placed in anti-A and anti-B sera?

It does not agglutinate in either.

What happens when type A blood is placed in anti-A serum?

It agglutinates.

What happens when type A blood is placed in anti-B serum?

It does not agglutinate.

What happens when type B blood is placed in anti-A serum?

It does not agglutinate.

What happens when type B blood is placed in anti-B serum?

It agglutinates.

Which ABO blood type is the most common in the United States?

Type O.

Which ABO blood type is the rarest in the United States?

Type AB.

What happens if type B blood is transfused into a type A recipient?

The recipient’s anti-B antibodies cause agglutination of the donor RBCs.

Why is type AB sometimes called the universal recipient?

Type AB plasma lacks both anti-A and anti-B antibodies.

What is an important limitation of calling type AB the universal recipient?

Donor plasma may still contain antibodies that can agglutinate the recipient’s RBCs.

Why is type O sometimes called the universal donor?

Type O RBCs lack A and B antigens.

What is an important limitation of calling type O the universal donor?

Type O donor plasma contains anti-A and anti-B antibodies that can agglutinate recipient RBCs.

Does a blood transfusion change a person’s blood type?

No. Blood type is fixed at conception.

What is the Rh blood group?

A blood group containing numerous RBC antigens, with C, D, and E being the principal types.

Which Rh antigen is the most reactive?

Antigen D.

What does Rh-positive (Rh+) mean?

The person has the D antigen.

What genotypes can produce Rh-positive blood?

DD or Dd.

What does Rh-negative (Rh−) mean?

The person lacks the D antigen.

What genotype produces Rh-negative blood?

dd.

Does ABO blood type determine Rh type?

No. ABO and Rh types are independent.

Are anti-D antibodies normally present in Rh-negative people?

No. They form only after exposure to Rh-positive blood.

What happens when an Rh-negative person receives Rh-positive blood?

The person becomes exposed to the D antigen and produces anti-D antibodies.

Why can a second Rh-positive transfusion be dangerous for an Rh-negative person?

Previously formed anti-D antibodies can attack the Rh-positive RBCs.

What is Rh incompatibility during pregnancy?

A situation in which an Rh-negative mother carries an Rh-positive fetus and can become sensitized to the fetus’s D antigen.

Why can a second Rh-positive pregnancy be dangerous?

The mother’s anti-D antibodies can cross the placenta and attack the fetus’s RBCs.

What is hemolytic disease of the newborn (HDN)?

Severe anemia in a fetus or newborn caused by destruction of RBCs by maternal antibodies.

What is another name for hemolytic disease of the newborn?

Erythroblastosis fetalis.

Is all HDN caused by Rh incompatibility?

No. About 2% of cases result from ABO or other blood-type incompatibilities.

How can Rh-related HDN be prevented?

An Rh-negative mother can be given Rh immune globulin, which prevents formation of anti-D antibodies.

What does Rh immune globulin do?

It binds fetal RBC antigens so the mother’s immune system does not produce anti-D antibodies.

Why can infants with HDN become severely anemic?

Maternal antibodies destroy their RBCs.

Why do infants with HDN release immature RBCs?

Their tissues increase RBC production to compensate for the anemia.

What can high bilirubin levels from RBC destruction cause?

Kernicterus.

What is kernicterus?

Toxic brain damage caused by high bilirubin levels.

How can HDN be treated with phototherapy?

Exposure to ultraviolet light helps degrade bilirubin as it passes through skin capillaries.

How can an exchange transfusion help treat HDN?

It replaces the infant’s Rh-positive blood with Rh-negative blood, allowing time for maternal antibodies to disappear.

How many other blood groups besides ABO and Rh are known?

At least 100 other blood groups are known.

What are examples of other blood groups?

MN, Duffy, Kell, Kidd, and Lewis.