Abo Blood Antigen System

Front 1

The A and B antigens are inherited as mendelian dominants. TRUE/FALSE

Back 1

TRUE. The A and B antigens are inherited as mendelian dominants.

Front 2

What exactly are the A and B antigens?

Back 2

They are complex oligosaccharides that differ in their terminal sugar.

Front 3

What are the chemical structures of these antigens on RBCs?

Back 3

They are mostly glycosphingolipids. On other tissues they are glycoproteins.

Front 4

What is an H gene?

Back 4

It codes for a fucose transferase that puts a fucose on the end of these glycolipids or glycoproteins, forming the H antigen that is present in individuals of all blood types.

Front 5

What is genetically unique about individuals who are type A?

Back 5

They have a gene which codes for a transferase that catalyzes placement of a terminal N-acetylgalactosamine on the H antigen.

Front 6

In type B individuals, what does the sugar gene code for?

Back 6

They have a gene which codes for a transferase that puts a terminal galactose.

Front 7

Individuals who are type AB have both transferases. TRUE/FALSE

Back 7

TRUE. Individuals who are type O have neither, yet the H antigen persists.

Front 8

Type O individuals have a single deletion in their corresponding gene. TRUE/FALSE

Back 8

TRUE.

Front 9

What are the subgroups of type A?

Back 9

A1 and A2. A1 cells have about 1,000,000 copies of the A antigen on its surface. A2 has about 250,000.

Front 10

Type A types develop anti-B antibodies. TRUE/FALSE

Back 10

TRUE. Type B develop anti A antibodies, O types develop both, and AB, neither.

Front 11

When does a hemolytic transfusion reaction occur?

Back 11

Blood is transfused into an individual with an incompatible blood type, an individual who has agglutinins against the RBCs in the transfusion.

Front 12

As RBCs are lysed, what happens to the Hg?

Back 12

Free Hg is liberated into the plasma. The severity of the reaction varies from a minor rise in plasma bilirubin level to severe jaundice and renal tubular damage, with potential anuria and death.

Front 13

Are persons with type AB blood universal recipients?

Back 13

Yes, but this statement should be qualified. They have no circulating agglutinins and can be given blood of any type usually w/o developing a transfusion reaction. In certain cases, reactions have been seen due to the presence of other unrecognized circulating antigens.

Front 14

Type O individuals are universal donors. TRUE/FALSE

Back 14

TRUE They lack A and B antigens.

Front 15

How is cross matching performed?

Back 15

Donor cells are mixed with recipients plasma on a slide and checked for agglutination. However, it is advisable to check the action of the donors plasma on the recipient cells in addition.

Front 16

Are there other agglutinogens besides the A and B type?

Back 16

Yes. There are systems such as Rh, MNSs, Lutheran, Kell and Kidd and many others.

Front 17

Certain diseases are more common in individuals with one blood type. TRUE/FALSE

Back 17

TRUE. The Duffy antigen is a chemokine receptor. The others are recognition molecules.

Front 18

The Rh antigen group is composed primarily of the C, D, and E antigens, though there are many more. TRUE/FALSE

Back 18

TRUE.

Front 19

When a person is Rh +, it generally means that the D antigen is dominant. TRUE/FALSE

Back 19

TRUE. This protein is not glycosylated.

Front 20

What percentage of caucasians are D positive?

Back 20

Approximately 85% of caucasians are positive. Over 99% of Asians are positive.

Front 21

Anti D antibodies do not develop without exposure of a D negative individual to D+ red cells by transfusion or entrance of fetal blood into maternal circulation. TRUE/FALSE

Back 21

TRUE. However, D neg individuals who have received a transfusion of D+ blood(even years before) can have appreciable anti D titers and may develop transfusion reactions when transfused again with D positive blood.

Front 22

What is hemolytic disease of the newborn?

Back 22

This arises when an Rh neg. mother carries an Rh positive fetus. Some fetal blood may leak into the maternal circulation at the time of delivery, and some mothers develop significant titers of anti Rh agglutinins during the postpartum period.

Front 23

What happens during a subsequent pregnancy regarding HDN?

Back 23

The mothers agglutinins cross the placenta to the fetus. Sensitization can occur during pregnancy. Fetal hemolysis can occur.(Erythroblastosis fetalis). The first pregnancy is usually not an issue of concern. Mothers develop significant titers of anti Rh agglutinins during the postpartum period.

Front 24

What are the consequences for the fetus?

Back 24

The fetus can die in utero. or develop anemia, severe jaundice and edema.(Hydrops fetalis).

Front 25

What is Kernicterus?

Back 25

It is a neurologic syndrome in which unconjugated bilirubin is deposited in the basal ganglia. This conditioned is worsened with hypoxia.

Front 26

Does bilirubin penetrate the brain in adults?

Back 26

Rarely, but it does in infants with this condition. The blood brain barrier is more permeable.

Front 27

Hemolytic disease occurs in about 17% of Rh positive fetuses born to Rh neg. mothers who have previously been preganant one or more times with Rh + fetuses. TRUE/FALSE

Back 27

TRUE.

Front 28

Is there treatment or prevention for this for this condition?

Back 28

Yes. By administering the first time a single dose of anti Rh antibodies in the form of Rh immune globulin, during the postpartum period.

Front 29

Does such treatment harm the mother?

Back 29

No. It has been demonstrated to prevent active antibody formation by the mother.