Kell Blood Group

Question 1

Compared to the Rh antigens how immunogenic are the Kell antigens?

Answer 1

Less immunogenic than Rh but overall the 2nd most immunogenic blood group system

Question 2

Why is anti-K able to cause extremely severe HDFN?

Answer 2

Antigens are very well expressed on fetal cells and they are also expressed well on erythroid precursor cells. Because of this not only are mature cells being destroyed.

Question 3

What protein is necessary to be present in order for the Kell antigen to be expressed?

Answer 3

XK protein

Question 4

What two genes are involved in the Kell antigen formation?

Answer 4

KEL gene on chromosome 7 codes for the Kell antigen itself. XK gene on the X chromosome codes for the Kx antigen that is necessary for the Kell antigen to be able to bind to the red cell. These are two independent genes.

Question 5

What are the low frequency Kell antigens?

Answer 5

Kp(a), Js(a)

Question 6

What are the high frequency Kell antigens?

Answer 6

Little k, Kp(b), Js(b)

Question 7

What is the frequency of the big K antigen?

Answer 7

9% positive for K antigen

Question 8

How does the K antigen react to enzyme treatment?

Answer 8

It is resistant to enzymes

Question 9

What immunoglobulin class is anti-K?

Answer 9

IgG

Question 10

At what temperature does anti-K react best?

Answer 10

37C body temperature

Question 11

Does anti-K cause HDFN and transfusion reactions?

Answer 11

Yes

Question 12

Does anti-K bind complement?

Answer 12

Some- about 20%

Question 13

When the Kp(a) antigen is expressed what will happen to the other Kell antigens?

Answer 13

The other antigens’ expression will be suppressed

Question 14

Which low frequency Kell antigen is found in about 20% of African Americans?

Answer 14

Js(a)

Question 15

What does DTT do and how does it affect the Kell antigens?

Answer 15

It dissociates IgM antibodies leaving only IgG antibodies. However it also breaks down the antigens of the Kell system.

Question 16

If someone inherits the K0 phenotype what Kell antigens do they express?

Answer 16

None, they do not form Kell antigens. They do form the Kx antigen.

Question 17

If an individual has the K0 phenotype what antibody are they able to form?

Answer 17

Anti-Ku (K5)

Question 18

If someone inherits the McLeod phenotype what antigens are they lacking?

Answer 18

Kx and Km antigens

Question 19

What happens to the Kell antigens when an individual lacks the Kx antigen?

Answer 19

The Kell antigen has issues binding. They still have some Kell antigen just a very small amount.

Question 20

What are the symptoms of McLeod Syndrome?

Answer 20

Acanthocytic RBCs, reduced in vivo RBC survival, chronic hemolytic anemia, muscle and nerve disorders, muscular dystrophy at 40-50 years, cardiomegaly

Question 21

With what disease is the McLeod phenotype associated?

Answer 21

Chronic Granulomatous Disease

Question 22

Since the Kx antigen is inherited on the X chromosome what happens if a female inherits one functioning XK gene and one non-functioning XK gene?

Answer 22

Only 1 X chromosome is active in every cell. They will exhibit two cell populations because a different one shuts down in every cell. Some will be normal, some will have the McLeod phenotype.

Question 23

What four instances can cause a weaker expression of the Kell antigens?

Answer 23

McLeod phenotype, Kp(a) gene expression, Gerbich negative phenotype, autoimmune hemolytic anemia directed against Kell.

Question 24

How might an individual express an acquired K antigen?

Answer 24

If the individual is infected with Streptococcus faecium, the bacteria can convert K- cell to K+. There cells will return to normal after the infection resolves.