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

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

Major Blood Group Systems Lewis I P MNSs Kell Kidd Duffy

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

Systems that Produce Cold-Reacting Antibodies

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

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-)

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

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

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

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

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

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

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

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

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

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)

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)

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

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

Thought….. Can a person have NO MNSs antigens? Yes, the Mk allele produces no M, N, S, or s antigens Frequency of 0.00064 or .064%

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

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

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

Systems that Produce Warm-Reacting Antibodies

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

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

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)

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

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

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

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)

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

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

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

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

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

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

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

Other Blood Group Antigens…

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

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)

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

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

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

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

Review

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

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

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

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)