1. Other Blood Group Systems
Renee Wilkins, PhD, MLS(ASCP)cm
CLS 325/435
School of Health Related Professions
University of Mississippi Medical Center

2. Facts Over 200 blood antigens exist!
Unfortunately, we only get to review the most relevant antigens
We will discuss each of these major antigens, their antibodies, and the clinical significance of each

3. Major Blood Group Systems
Lewis I P
MNSs
Kell
Kidd
Duffy

4. Basic terms to remember
Clinical significance: antibodies that are associated with decreased RBC survival
Transfusion reactions
HDN
Not clinically significant: antibodies that do not cause red cell destruction
Cold reacting antibodies: agglutination best observed at or below room temp.
Warm reacting antibodies: agglutination best observed at 37°C

5. Systems that Produce Cold-Reacting Antibodies

6. Lewis substance adheres to RBC becoming an antigen
Lewis Antigens
Soluble antigens produced by tissues and found in body fluids (plasma)
Adsorbed on the RBC
Lewis substance adheres to RBC becoming an antigen
RBC
Le substance in plasma
Le genes

7. Lewis inheritance Lewis system depends on Hh, Se, and Le genes
le, h, and se do not produce products
If the Le gene is inherited, Lea substance is produced
Le, H, and Se genes must ALL be inherited to convert Lea to Leb. Examples:
Le se H  Le(a+b-)
Le Se H  Le(a-b+)
le H se  Le(a-b-)
le hh se  Le(a-b-)

8. Lewis Antibodies Usually occur naturally in those who are Le(a-b-)
Other phenotypes RARELY produce the antibody
IgM (may fix complement, becoming hemolytic)
Enzymes enhance activity
May be detected soon after pregnancy because pregnant women may temporarily become Le(a-b-)
No clinical significance…Why?
Le antibodies in a patient can be neutralized by the Lewis antigens in the donor’s plasma (cancel each other out)
do not cause HDN because they do not cross placenta (antigens not developed well in cord blood)
Le(a-b-)
May become hemolytic in vitro (in the tube)
If pregnant women have Le antibodies detected, they need to first be neutralized so that HDN antibodies may be detected

9. I antigens These antigens may be I or i
They form on the precursor chain of RBC
Newborns have i antigen
Adults have I antigen
i antigen (linear) converts to I (branched) as the child matures (precursor chain is more linear at birth) at about 18 months

10. I antibodies Most people have autoanti-I (RT or 4°C)
Alloanti-I is very rare
Cold-reacting (RT or below) IgM antibody
Clinically insignificant
Can attach complement (no hemolysis unless it reacts at 37°)
Prewarming the tests can eliminate reactivity
Enzymes can enhance detection

11. I antibodies Anti-I often occurs as anti-IH
This means it will react at different strengths with reagent cells (depending on the amount of H antigen on the RBC)
O cells would have a strong reaction
A cells would have a weaker reaction

12. Anti-I antibodies Anti-I: Anti-i:
Associated as a cause of Cold Agglutinin Disease (similar to PCH)
May be secondary to Mycoplasma pneumoniae infections
Anti-i:
rare and is sometimes associated with infectious mononucleosis
PCH- paroxysmal cold hemoglobinuria

13. P Antigen Similar to the ABO system
The most common phenotypes are P1 and P2
P1 – consists of P1 and P antigens
P2 – consists of only P antigens
Like the A2 subgroup, P2 groups can produce anti-P1
75% of adults have P1

14. P1 Antigen Strength of the antigen decreases upon storage
Found in secretions like plasma and hydatid cyst fluid
Cyst of a dog tapeworm

15. P antibodies Anti-P1 Anti-P Naturally occurring IgM
Not clinically significant
Can be neutralized by hydatid cyst fluid to reveal more clinically significant antibodies
Anti-P
Produced in individuals with paroxysmal cold hemoglobinuria (PCH)
PCH – IgG auto-anti-P attaches complement when cold (fingers, toes). As the red cells circulate, they begin to lyse (releasing Hgb)
This PCH antibody is also called the Donath-Landsteiner antibody

16. MNSs Blood System 4 important antigens (more exist):
U (ALWAYS present when S & s are inherited)
M & N located on Glycophorin A
S & s and U located on Glycophorin B
Remember: Glycophorin is a protein that carries many RBC antigens

17. MNSs Antigens
M & N only differ in their amino acid sequence at positions 1 and 5 M
Glycophorin A N
RBC
S & s only differ in their amino acid sequence at position 29 S U s
Glycophorin B
COOH end …..
….5, 4, 3, 2, 1 (NH2 end)

18. MNSs antigens all show dosage
M & N give a stronger reaction when homozygous, (M+N-) or (M-N+)
Weaker reactions occur when in the heterozygous state (M+N+)
Antigens are destroyed by enzymes (i.e. ficin, papain)

19. U (Su) antigen
The U antigen is ALWAYS present when S & s are inherited
About 85% of S-s- individuals are U-negative (RARE)
U-negative cells are only found in the Black population

20. Frequency of MNSs antigens
Phenotypes
Blacks (%)
Whites (%) M+ 74 78 N+ 75 72 S+
30.5 55 s+ 94 89 U+ 99
99.9
High-incidence antigen

21. Thought….. Can a person have NO MNSs antigens?
Yes, the Mk allele produces no M, N, S, or s antigens
Frequency of or .064%

22. Anti-M and anti-N antibodies
Demonstrate dosage
Anti-M and anti-N
IgM (rarely IgG)
Clinically insignificant
If IgG, could be implicated in HDN (RARE)
Will not react with enzyme treated cells

23. Anti-S, Anti-s, and Anti-U
Clinically significant
IgG
Can cause RBC destruction and HDN
Anti-U
will react with S+ or s+ red cells
Usually occurs in S-s- cells
Can only give U-negative blood units found in <1% of Black population
Contact rare donor registry

24. MNSs Antibody Characteristics
IgG Class
Clinically significant
Anti-M
IgM (rare IgG) No
Anti-N
IgM
Anti-S
IgG
Yes
Anti-s
Anti-U

25. Systems that Produce Warm-Reacting Antibodies

26. Kell System Similar to the Rh system 2 major antigens (over 20 exist)
K (Kell), <9% of population
k (cellano), >90% of population
The K and k genes are codominant alleles on chromosome 7 that code for the antigens
Well developed at birth
The K antigen is very immunogenic (2nd to the D antigen) in stimulating antibody production

27. Other Kell antigens
Other sets of alleles also exist in the Kell system:
Analogous to the Rh system: C/c and E/e
Kp antigens
Kpa is a low frequency antigen (only 2%)
Kpb is a high frequency antigen (99.9%)
Js antigens
Jsa (20% in Blacks, 0.1% in Whites)
Jsb is high frequency (80-100%)
Kpa = Penney
Kpb = Rautenberg
Jsa = Sutter
Jsb = Matthews

28. Kell antigens
Kell antigens have disulfide-bonded regions on the glycoproteins
This makes them sensitive to sulfhydryl reagents:
2-mercaptoethanol (2-ME)
Dithiothreitol (DTT)
2-aminoethylisothiouronium bromide (AET)

29. Kellnull or K0
No expression of Kell antigens except a related antigen called Kx
As a result of transfusion, K0 individuals can develop anti-Ku (Ku is on RBCs that have Kell antigens)
Rare Kell negative units should be given

30. Kell antibodies IgG (react well at AHG)
Produced as a result of immune stimulation (transfusion, pregnancy)
Clinically significant
Anti-K is most common because the K antigen is extremely immunogenic
k, Kpb, and Jsb antibodies are rare (many individuals have these antigens and won’t develop an antibody)
The other antibodies are also rare since few donors have the antigen

31. Kx antigen Not a part of the Kell system, but is related
Kx antigens are present in small amounts in individuals with normal Kell antigens
Kx antigens are increased in those who are K0

32. McLeod Syndrome
The XK1 gene (on the X chromosome) codes for the Kx antigen
When the gene is not inherited, Kx is absent (almost exclusive in White males)
Causes abnormal red cell morphologies and decreased red cell survival:
Acanthocytes – spur cells (defected cell membrane)
Reticulocytes – immature red cells
Associated with chronic granulomatous disease
WBCs engulf microorganisms, but cannot kill (normal flora)

33. Kidd Blood Group 2 antigens Jka and Jkb (codominant alleles)
Show dosage
Genotype
Phenotype
Whites (%)
Blacks (%)
JkaJka
Jk(a+b-)
26.3
51.1
JkaJkb
Jk(a+b+
50.3
40.8
JkbJkb
Jk(a-b+)
23.4
8.1
JkJk
Jk(a-b-)
rare

34. Kidd Antigens Well developed at birth Enhanced by enzymes
Not very acessible on the RBC membrane

35. Kidd antibodies Anti-Jka and Anti-Jkb IgG Clinically significant
Implicated in HTR and HDN
Common cause of delayed HTR
Usually appears with other antibodies when detected

36. Kidd antibodies Anti-Jk3 Found in some individuals who are Jk(a-b-)
Far East and Pacific Islanders (RARE)

37. Duffy Blood Group Predominant genes (codominant alleles):
Fya and Fyb code for antigens that are well developed at birth
Antigens are destroyed by enzymes
Show dosage
Phenotypes
Blacks
Whites
Fy(a+b-) 9 17
Fy(a+b+) 1 49
Fy(a-b+) 22 34
Fy(a-b-) 68
RARE

38. Duffy antibodies IgG Do not bind complement Clinically significant
Stimulated by transfusion or pregnancy (but not a common cause of HDN)
Do not react with enzyme treated RBCs

39. The Duffy and Malaria Connection
Most African-Americans are Fy(a-b-)
Interestingly, certain malarial parasites (Plasmodium knowlesi and P. vivax) will not invade Fya and Fyb negative cells
It seems either Fya or Fyb are needed for the merozoite to attach to the red cell
The Fy(a-b-) phenotype is found frequently in West and Central Africans, supporting the theory of selective evolution

40. Other Blood Group Antigens…

41. Lutheran Blood Group System
2 codominant alleles: Lua and Lub
Weakly expressed on cord blood cells
Most individuals (92%) have the Lub antigen, Lu(a-b+)
The Lu(a-b-) phenotype is RARE

42. Lutheran antibodies Anti-Lua Anti-Lub IgM and IgG
Not clinically significant
Reacts at room temperature
Mild HDN
Naturally occurring or immune stimulated
Anti-Lub
Rare because Lub is high incidence antigen
IgG
Associated with transfusion reactions (rare HDN)

43. Bg Antigens Three (Bennett-Goodspeed) Bg antigens:
Bgb
Bgc
Related to human leukocyte antigens (HLA) on RBCs
Antibodies are not clinically significant

44. Sda Antigens High incidence antigens found in tissues and body fluids
Antibodies are not clinically significant
Antibodies characteristically cause mixed field agglutination with reagent cells

45. Xg Blood Group Only one exists (Xga)
Inheritance occurs only on the X chromosome
89% Xga in women
66% in males (carry only one X)
Men could be genotype Xga or Xg
Women could be XgaXga, XgaXg, or XgXg
Example: Xg(a+) male with Xg(a-) woman would only pass Xg(a+) to daughters, but not sons
The antigen is not a strong immunogen (not attributed to transfusion reactions); but antibodies may be of IgG class

46. HTLA Antigens High Titer Low Avidity (HTLA) Occur with high frequency
Antibodies are VERY weak and are not clinically significant
Do not cause HDN or HTR

47. Review

48. Cold Antibodies (IgM) LIiPMABHN Anti-Lea Anti-Leb Anti-I Anti-P1
Anti-M
Anti-A, -B, -H
Anti-N
LIiPMABHN
Naturally Occurring

49. Warm antibodies (IgG)
Rh antibodies
Kell
Duffy
Kidd
S,s

50. Remember enzyme activity:
Enhanced by enzymes
Destroyed by enzymes
Kidd Rh
Lewis I P
Fya and Fyb
M, N
S, s
Papain, bromelin, ficin, and trypsin

51. Remembering Dosage: Kidds and Duffy the Monkey (Rh) eat lots of M&Ns
Jka, Jkb, Fya, Fyb, C, c, E, e (no D), M, N, S, s
MNSs
Kidd
Duffy Rh
adapted from Clinical Laboratory Science Review: A Bottom Line Approach (3rd Edition)