1. Other Blood Group Systems
Terry Kotrla, MS, MT(ASCP)BB

2. Introduction Over 500 blood group antigens
“High incidence”, “public” or “high frequency” antigens are those present on almost every person’s red blood cells
“Low incidence”, “private” or “low frequency” antigens are present on very, very few individuals red blood cells

3. Introduction
Each known antigen initially identified through the detection of its specific antibody in the serum.
Knowledge of serologic behavior and characteristics of blood group antibodies is CRITICAL for identification

4. Introduction
Essential when evaluating antibody screen and panel studies.
Considerations given to:
Phase of reactivity
Antibody class involved
Ability to cause HDFN and HTR

5. I Blood Group Related to ABO and Lewis by its biochemical structure
Two antigens: I and i
Fetal RBCs rich in i antigen and lack I antigen.
First 2 years I develops, lose i
Anti-I reacts most strongly with adult cells, negative or weakly with cord RBCs
Strength of I antigen varies on adult cells
Rare instances I never develops.

6. I Blood Group
Anti-I is associated with cold agglutinin hemagglutinin disease
Decreased expression of I and increased expression of i antigens is observed in:
oncogenesis,
thalassemias,
sickle cell anemias,
associated with congenital cataracts in Asian populations.

7. I Blood Group Antibodies: anti-I anti-I Anti-I
Cause of non-specific agglutination in tests performed at RT
Positive reactions with all cells tested: reverse, antibody screen and crossmatches
May cause ABO discrepancy
Can be detected in serum of most normal adults if serum is tested at 4C
Associated with atypical pneumonia caused by M. pneumoniae , cold agglutinin titers used to monitor the disease.
May cause hemolytic anemia when present in high titers

8. I Blood Group Anti-i associated with certain diseases
Infectious mononucleosis
Epstein-Barr virus
Cytomegalovirus
Antibody is rarely encountered

9. I Blood Group Clinical Significance Usually benign
Clinically significant examples seen in Cold Agglutinin Syndrome (CAS)
Antibodies are of high titer (1000>)
High thermal amplitude
Cause hemolytic anemia
Transfuse blood through blood warmer
Cannot cause HDFN
Does not cause HTR

10. I Blood Group Serological Confirmation
Test serum agains 3 adult O RBCs and 3 cord RBCs and an auto-control
Adult cells and auto-control = positive
Cord RBCs = negative/very weak positive
Prewarmed technique will eliminate reactivity of most examples
Reactivity enhanced using enzyme treated cells

11. I Blood Group
Very strong examples of anti-I may react at AHG and require cold autoabsorption or rabbit erythrocyte stroma test (REST) to rule out presence of other antibodies.
Collect EDTA blood samples, place at 37C
Harvest EDTA cells, wash with 37C saline
Place clotted blood sample at 4C, separate serum
Add 1 mL serum to 1mL rbcs, incubate at 4C for 1 hour
Harvest serum and test against screen cells, if negative, continue screen, if positive repeat absorption with new aliquot of RBCs

12. Lewis System
Major antigens Lea and Leb , other antigens include Lec, Led and Lex
Antigens ARE NOT intrinsic to RBCs but are absorbed from the plasma and inserted into RBC membrane.

13. Lewis System Antigenic Development
Genetic control reside in single gene “Le”
Amorph le, if homozygous will not have Lewis antigens
Lea formed first, then modified to form Leb which is adsorbed preferentially over Lea
Lewis phenotype of RBC can be changed by incubating with plasma containing Lea or Leb glycoplipid.

14. Lewis System Lewis Phenotypes and Their Frequencies White Black
Le (a+b-)
22%
23%
Le (a-b+)
72%
55%
Le (a-b-) 6%
Le (a+b+)
Rare
rare

15. Lewis System Lewis antigens in infants
Antigens absent or extremely weak at birth
Expression of Leb gradual
Birth Le (a-b-)
2 months Le(a+b-)
12 to 18 months Le(a+b+)
2 to 3 years Le (a-b+)

16. Lewis System Lewis antigens and pregnancy
Antigen strength may decline dramatically
Transiently Le (a-b-) may produce Lewis antibodies during pregnancy
Antigens return after delivery and antibodies disappear

17. Lewis System Interaction of Le, Se and H Genes
lele will not have Lewis antigens, but if Se present will have A, B and H in secrections
Genotype se/se and have one Lewis antigen will have Lea in their secretions but no A, B or H.

18. Lewis System Le (a+b-) Le (a-b+) Le (a-b-) Lewis Phenotype
ABH Secretor
Lewis Secretor
Le (a+b-)
All ABH NON-Secretors
All Lea Secretors
Le (a-b+)
All ABH secretors
All secretors of Lea and Leb
Le (a-b-)
80% ABH secretors
20% ABH NON secretors
NONE

19. Lewis System Lewis Antibodies
Almost always IgM, react strongly at RT, may cause ABO discrepancy if reverse cells have Lewis antigen.
Occur almost exclusively in Le (a-b-) and production of anti-Lea AND –Leb not unusual
Anti-Lea frequently encountered, anti-Leb rarely encountered.

20. Lewis System Lewis Antibodies
Although most react at RT reactivity may be seen at 37C, but is weaker and may be weakly reactive at AHG
Can bind complement and cause IN-VITRO hemolysis, most often with enzyme treated cells
Because antibodies are IgM and antigens are poorly developed at birth antibodies NOT implicated in HDFN.

21. Lewis System Lewis antibodies
Can be neutralized in-vitro by additions of Lewis Substance
Le antigens are present in secretions
Add to serum with Lewis antibodies and the antibodies will be bound to the soluble Lewis antigens
Useful when multiple antibodies are present and 1 is a Lewis, eliminates the activity of the antibody

22. Lewis System Transfusion Practice
Transfused RBCs will acquire the Lewis phenotype of the recipient within a few days
Lewis antibodies in patient will be neutralized by Lewis substance in donor plasma
Lewis antibodies rarely cause in-vivo hemolysis
It is not necessary to phenotype donors for Lewis antigens prior to transfusion, give crossmatch compatible

23. P Blood Group Whites Blacks P1 79% 94% P2 21% 6%
Discovered 1927 when Landsteiner immunized rabbits with human RBCs
Initially named “P” but as complexity of P blood group was discovered renamed “P1”
RBCs lacking P1 are P2
Other P phenotypes exist but are rare(<1%): P, P1k and P2k
Whites
Blacks P1
79%
94% P2
21% 6%