Kell

Question 1

How many antigens are there in the Kell blood group?

Answer 1

35

Question 2

What type of membrane structure is the Kell antigen?

Answer 2

Single-pass glycoprotein that is highly folded

Question 3

How many amino acids does the Kell antigen have?

Answer 3

732

Question 4

How is the Kell antigen made?

Answer 4

KEL gene on chromosome 7

Question 4

How is the Kell antigens affected by papain enzyme treatment?

Answer 4

Resistant but with variable reactions, e.g. pos reaction by IAT but weaker or undetected by ENZ

Question 5

When are the Kell antigens formed?

Answer 5

Present in the early fetal life and well developed at birth

Question 5

Which are the two major antibodies commonly encountered?

Answer 5

K and k (cellano)

Question 5

Are K and k codominant?

Answer 5

Yes

Question 5

What amino acid is needed to make the K antigen?

Answer 5

Methionine

Question 6

How many amino acid change is there between K and k?

Answer 6

1

Question 6

What amino acid is needed to make the k antigen?

Answer 6

threonine

Question 7

At what position is the amino acid change between K and k?

Answer 7

193

Question 8

What is the % frequency of K+k- (KK genotype) in the black population?

Answer 8

0%

Question 9

What is the % frequency of K+k- (KK genotype) in the white population?

Answer 9

0.2%

Question 10

What is the % frequency of K+k+ (Kk genotype) in the black population?

Answer 10

1.5%

Question 11

What is the % frequency of K+k+ (Kk genotype) in the white population?

Answer 11

8.8%

Question 12

What is the % frequency of K-k+ (kk genotype) in the black population?

Answer 12

91%

Question 13

What is the % frequency of K-k+ (kk genotype) in the white population?

Answer 13

98.5%

Question 14

Is K clinically significant?

Answer 14

Yes, most immunogenic antigen after RhD so often seen in transfusion recipients. Anti-K can be on its own or in conjunction with other antibodies.
Severe transfusion reaction and severe HDFN

Question 15

What other Kell antigens are often seen?

Answer 15

Kpa
Kpb
Jsa
Jsb

Question 16

What type of immunoglobulin are the Kell antigens mentioned?

Answer 16

IgG

Question 17

Can the Kell antigens activate complement?

Answer 17

Unlikely and rare with anti-K

Question 18

What is the optimal technique to detect the Kell antigens?

Answer 18

IAT at 37oC

Question 19

Which of the Kell antibodies are capable of initiating a transfusion reaction and HDFN?

Answer 19

anti-K
anti-k
anti-Jsa
anti-Jsb

Question 20

What is the % occurrence of the K antigen in the black population?

Answer 20

1.5%

Question 21

What is the % occurrence of the K antigen in the white population?

Answer 21

9%

Question 22

What is the % occurrence of the k antigen in the black population?

Answer 22

100%

Question 23

What is the % occurrence of the k antigen in the white population?

Answer 23

99.8%

Question 24

What is the % occurrence of the kpa antigen in the black population?

Answer 24

0%

Question 25

What is the % occurrence of the kpa antigen in the white population?

Answer 25

2%

Question 26

What is the % occurrence of the kpb antigen in the black population?

Answer 26

100%

Question 27

What is the % occurrence of the kpb antigen in the white population?

Answer 27

>99.9%

Question 28

What is the % occurrence of the Jsa antigen in the black population?

Answer 28

20%

Question 29

What is the % occurrence of the Jsa antigen in the white population?

Answer 29

<0.01%

Question 30

What is the % occurrence of the Jsb antigen in the black population?

Answer 30

99%

Question 31

What is the % occurrence of the Jsb antigen in the white population?

Answer 31

100%

Question 32

Why is it not essential to have a rarer phenotype K+k- red cells for antibody screening or ABID panels?

Answer 32

Anti-K is typically avid and will react strongly with K+k+ and K+k-

Question 33

How would you provide RBC to a patient with anti-K or anti-k?

Answer 33

Antigen negative crossmatch compatible at 37oC

Question 34

How easy is it to get antigen negative blood for K and k?

Answer 34

K = easy as 9/10 donors will be K neg in UK and all units are antigen K typed k = difficult (HFA) 1/500 donors

Question 35

Is anti-Kpa clinically significant?

Answer 35

Sometimes e.g. in pregnancy. Can cause transfusion reactions and HDFN with mild to severe cases but rare so Kpa neg cells is not necessary for antibody screening

Question 36

Why is anti-Kpb considered a nuisance antibody?

Answer 36

Because the majority of the population is Kpb antigen positive so will react with almost all donations therefore it is very difficult to source Kpb negative blood

Question 37

How common is anti-Jsa and Jsb?

Answer 37

In the UK it is uncommon because the nature of the donor population most patient and donor is Js(a-b+). But if present must be treated as clinically significant

Question 38

What causes the Kell null phenotype (Ko)?

Answer 38

Homozygous inheritance of non-functioning KEL genes resulting in absence of entire KELL glycoprotein

Question 39

What would happen if a Ko patient is transfused with a non Ko RBC unit?

Answer 39

They can make anti-Ku which is clinically significant causeing both transfusion reactions and HDFN. Can also be made through pregnancy.