P Blood Group

Question 1

What are the 3 antigens of the P system?

Answer 1

P1, P, Pk

Question 2

What are the 5 phenotypes of the P system?

Answer 2

P1, P2, p, P1k, P2k

Question 3

The P genes code to make what type of proteins? What is the function of these proteins?

Answer 3

Glycosyltransferases, their function is to add sugars to a precursor substance

Question 4

Which antigens does the P1 phenotype have?

Answer 4

P1, P, Pk

Question 5

When storing cells with the P1 antigen for a longer period of time, what happens to the antigen?

Answer 5

It deteriorates

Question 6

At what point in life is the P1 antigen fully developed?

Answer 6

7 years

Question 7

Which phenotypes will produce an anti-P1?

Answer 7

P2 and P2k. These lack the P1 antigen. Even though p also lacks the antigen, it makes an antibody in a combined form of anti-PP1Pk

Question 8

Is anti-P1 an immune or naturally occurring antibody?

Answer 8

Naturally occurring

Question 9

Is anti-P1 typically an IgM or IgG antibody?

Answer 9

IgM

Question 10

At what temperature does anti-P1 react best?

Answer 10

Room temperature or colder

Question 11

Why is anti-P1 not a cause of HDFN?

Answer 11

It is IgM and can’t cross the placenta and the P1 antigen is poorly developed on fetal RBCs

Question 12

Approximately what percentage of the population is positive for the P1 phenotype?

Answer 12

80%

Question 13

What substances can be used to neutralize P1 antibody?

Answer 13

Hydatid Cyst fluid from Echinococcus granulosus and Avian P1 substance (in dropping of pigeons and turtle doves)

Question 14

The P2 phenotype lacks which antigen(s)?

Answer 14

P1, it contains the P and Pk antigens

Question 15

Approximately what percentage of the population has the P2 phenotype?

Answer 15

20%

Question 16

If an individual inherits the P1k phenotype, what antigens do they form?

Answer 16

P1 and Pk (lack the P antigen)

Question 17

If an individual inherits the P2k phenotype, what antigens do they form?

Answer 17

Pk (lack P1 and P antigens)

Question 18

What antibody could a P1k individual form?

Answer 18

Anti-P

Question 19

If an individual inherits the p phenotype, what antigens do they form?

Answer 19

None

Question 20

What antibody can an individual with the p phenotype form?

Answer 20

Anti-PP1Pk

Question 21

Can an anti-PP1Pk cause transfusion reactions and HDFN?

Answer 21

Yes

Question 22

Which P system antibody is usually seen as an autoantibody?

Answer 22

Autoanti-P

Question 23

Which antibody is the cause of Paroxysmal Cold Hemoglobinuria?

Answer 23

Autoanti-P

Question 24

In what demographic is Paroxysmal Cold Hemoglobinuria usually seen?

Answer 24

Secondary to viral infections in young children

Question 25

Describe the process by which the autoantibody destroys red cells in Paroxysmal Cold Hemoglobinuria?

Answer 25

The antibody is biphasic- the antibody binds in the cold (when blood is in your extremities) and lyses when the body temp rises (in your core)

Question 26

What is the recommended treatment for Paroxysmal Cold Hemoglobinuria?

Answer 26

Stay away from the cold

Question 27

Describe how the Donath-Landsteiner test is performed.

Answer 27

Patient serum (with potential autoanti-P) is added to P+ cells in 2 different tubes. The first tube is incubated at 37C for 60 min. The second tube is incubated at 4C for 30 minutes and 37C for another 30 minutes. If the autoanti-P is present the tube that was incubated in the cold first and then the warm should have hemolyzed the red cells causing the serum to be red. The tube kept at warm temperatures should remain clear and yellow.

Question 28

What is the typical DAT reaction of a patient with Paroxysmal Cold Hemoglobinuria?

Answer 28

Polyspecific reagent is positive, anti-IgG reagent is negative, and anti-C3d is positive

Question 29

Individuals with which P system phenotypes will lack the Luke antigen?

Answer 29

Pk phenotypes and p phenotype

Question 30

Do the majority of people have the Luke antigen or lack the Luke antigen?

Answer 30

The majority are Luke antigen positive