Kell

Question 1

What Chromosome is KEL located on?

Answer 1

Chromosome 7

Question 2

When can Kell antigens be detected during gestation?

Answer 2

7-10 weeks gestation

Question 3

What cells are Kell found on?

Answer 3

Only RBC’s

Question 4

What is the frequency of K?

Answer 4

9% of whites are positive

3% of Blacks are positive

Question 5

What is the frequency of k?

Answer 5

High Freq
0.2% Whites are negative
<0.1% Blacks are negative

Question 6

What is the frequency of Jsa?

Answer 6

Jsa + seen in blacks

20% are positive

Question 7

What is the frequency of Jsb?

Answer 7

High freq
1% of blacks are negative (Jsa/Jsa)
Anti-Jsb seen in black population

Question 8

What is the frequency of Kpa?

Answer 8

2% are postive

Question 9

What is the frequency of Kpb?

Answer 9

<0.1% are Kpb negative

Question 10

Characteristics of anti-K

Answer 10

K antigen is second to D for antigenicity
A K- person receives K+ there is a 10% chance they will make anti-K
May activate complement, cause TRN RXN, and HDFN
Usually IgG1 reacts at 37C with AHG
Can show dosage
Can be naturally occurring and sometimes reacts at RT

Question 11

How does anti-K cause HDFN?

Answer 11

Kell antigens are present on early RBC precursor cells before hgb is present. Macropages in the fetal liver phagocytsis cells. Reduced retics and low bilirubin.
Antibody titers don’t predict severity of disease

Question 12

What gene affects Kell expression?

Answer 12

Kell antigen expression depends on XK gene that produces Kx protein
Kx antigen spans the membrane 10X

Question 13

What chromosome is the XK gene located on?

Answer 13

X chromosome

Question 14

What is Kpc?

Answer 14

3 allelle antithetical to Kpa and Kpb
Low frequency
Found in Japan

Question 15

What is the amino acid that defines K?

Answer 15

Methionine

Same as S

Question 16

What is the amino acid that defines k?

Answer 16

Threonine

Same as s

Question 17

What are the low frequency antigens in the Kell system?

Answer 17

UIa, K23, and KYO

Question 18

What antigens does DTT destroy?

Answer 18

KEL, JMH, LW, Lutheran, Dombrock, Cromer, Knops

Does not destroy Kx antigen

Question 19

What is the effect of enzymes on Kell antigens?

Answer 19

Kell antigens are resistant

Question 20

What are the Kell haplotypes?

Answer 20

k, Kpb, Jsb are inherited together
Only one mutation can occur per haplotype
Can Type as K+ and Kpa+ if inherited one from each parent. Does not occur on same haplotype
Closely linked so crossing over doesn’t occur

Question 21

How is Kx expression effected by Kell antigen expression?

Answer 21

Kx is weak when Kel antigens are present
Anti-Kx reacts strongly with KoKo cells with no Kell antigens
The less Kell antigen the stronger Kx antigen

Question 22

What potentiator enhances Kell antibody?

Answer 22

PEG can enhance reactivity

Some anti-K will react poorly with LISS or in Automated systems

Question 23

What is the structure of Kel antigen?

Answer 23

its a type II membrane glycoprotien that spans the membrane once
It is connected to Kx with a single disulfide bond
the glycoprotein is highly folded by disulfide linkages = DTT destroys

Question 24

Why are Kell autoantibodies formed?

Answer 24

There may be a transient depression of Kell antigens due to disease
Autoantibodies can be benign or hemolytic
Will react with all except Ko cells

Question 25

What is Ku?

Answer 25

KEL5
U stands for universal antigen
Present when Kell glycoprotein is present; absent in Ko cells

Question 26

What is Km?

Answer 26

KEL20

Thought to be a product of the interaction of Kx and Kell. Both must be present for expression

Question 27

What is the Ko phenotype?

Answer 27

Kell is silenced = no Kell antigens
No Ku or Km
Can make anti-Ku and other Kell antibodies
Kx will be strongly expressed
Ko heterozygotes will have normal K antigen
Occurs 1 in 25,000 whites

Question 28

What is the Mcleod Phenotype?

Answer 28

Very rare. No XK gene.
No Kx or Km
Kell antigens are very weak. May need absorb/elute.
W/ CGD = Make anti-Kx or Km
W/O CGD = Only make anti-Km (Ko cells compatible)

Question 29

What abnormalities are caused by Mcleod syndrome?

Answer 29

Acathocytosis, Retic’s, compensated hemolytic anemia
Muscular and neurological abnormalities
Muscle wasting, reduction in deep tendon reflexes
Increased CPK enzymes
Can have Mcleod phenotype w/o syndrome

Question 30

What disease is associated with Mcleod Phenotype?

Answer 30

Some individuals will also have chronic granulomatous disease (CGD)
Causes recurrent bacterial infections early in life that result in death
Granulocytes phagocytize but unable to kill

Question 31

What causes weak Kell antigen expression?

Answer 31

1. When Kpa is present Kell antigens are weakend due to a reduced amount of Kell glycoprotein
2. Kmod phenotype have reduced Kell expression but increased Kx
3. Leach phenotype = Gerbich negative cells have a weak Kell antigens

Question 32

What antibody is made by Kmod individuals?

Answer 32

Some make Ku like antibody

Question 33

What donors should you screen for Kpb negative and Jsb negative blood?

Answer 33

Kpb negative is more common in whites

Jsb negative is more common in blacks

Question 34

What antibody will react strongly with DTT treated cells?

Answer 34

Anti-Kx. DTT destroys the Kell antigen so Kx is enhanced

Question 35

What chemicals will destroy Kell antigens?

Answer 35

DTT, AET, ZZAP, and EGA destroys kell antigens

Question 36

What cells will anti-Kx react with?

Answer 36

Weakly with normal cells (blocked by Kell antigens)
Strongly with DTT treated cells
Strongly with Ko and Kmod cells
Negative with Mcleod (No Kx)

Question 37

What cells will anti-Km react with?

Answer 37

Km expressed with Kell and Kx are present
Positive with normal cells
Negative with Ko and Mcleod cells
Strongly positive with Kmod cells

Question 38

What cells will anti-Ku react with?

Answer 38

Positive with normal cells
Weakly with McLeod and Kmod cells
Negative with Ko cells