Terry Kotrla, MS, MT(ASCP)BB

Unit 9 Other Blood Group SystemsPart 2

Systems that Produce Cold-Reacting Antibodies

Covered So FarIiLewisP

MNSs Blood System (ISBT 002)4 important antigens (more exist):

MNSsU (ALWAYS present when S & s are inherited)

AntibodiesM – antibodies USUALLY reactive at RTN - antibodies USUALLY reactive at RTS – antibodies are clinically significants – antibodies are clinically significantU - antibodies are clinically significant

MNSs Antibodies – General InformationAll show dosageM & 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)

DosageCell IS 37 IgG

1 M+N= (MM) 3+ 1+ 0

2 M+N+ (MN) 2+ 0 0

3 N+N+ (NN) 0 0 0

Cell 1 is homozygous for M, it has a “double” dose of the antigen and all antigens on the cell for this blood group will be M. Notice the 3+ reaction.

Cell 2 is heterozygous, a single dose of each, only 50% of the antigens will be M and 50% will be N. Notice the 2+ reaction

Because there are a decreased number of ANTIGENS you will expect DECREASED serologic reactivity.

When varying strengths of reactions are noted within a single phase of reactivity THINK DOSAGE first and multiple antibodies second.

Anti-MFrequently detected as a naturally occurring

saline agglutinin at RT testing.Most examples occur WITHOUT red cell stimulus.Weak examples of the antibody can be enhanced

by “acidifying” the serum, lowering the pH to 6.5.RARE examples have been found that are partly

or wholly IgG which have caused HDFN or HTRMOST are clinically INSIGNIFICANT, no HDFN or

HTR.Do NOT need to confirm donors are M negative,

must be crossmatch compatible.Will NOT react with enzyme treated cells.

Anti-NRarely encountered.IgM Typically weakly reactive at RTConsidered clinically insignificant although

RARE examples of IgG have been observed.Do NOT need to confirm donors are M

negative, must be crossmatch compatible.Will NOT react with enzyme treated cells.

N Typing ReagentLectin extracted from Vicia graminea has

specificity for N antigen.Add to test RBCs as well as positive and

negative controls.N antigen present = positive agglutination

reaction.N antigen absent = negative agglutination

reaction.

Variant MN Antigen Mg

VERY RAREPerson with genotype Mg N will test as

M=N+ leading to false conclusion that genotype is NN.

Of primary importance in paternity testing.

S, s and U AntigensS and s produced by pair of allelic antigens

at locus closely linked to MN locus.

White Black

S+s=U+ 11% 3%

S+s+U+ 44% 28%

S=s+U+ 45% 69%

S=s=U= 0% Less than 1%

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

S, s and U AntibodiesClinically significantIgGCauses HDFN and HTRWill NOT react with enzyme treated cells,

antigens are destroyed by enzyme treatment.

Must confirm that donor units are negative for antigen(s).

Donor units must be crossmatch compatible.

U (Su)The U antigen is ALWAYS present when S and s

are inheritedEstablish as U negative by proving they are S=s=.Can only give U-negative blood units found in <1% of

Black populationSuspect anti-U when a pregnant or previously

transfused black individual reacts with ALL cells tested and has a negative autocontrol.

Will NOT find U negative blood in any population except the black population.

Two potential sources are siblings and rare donor blood.

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%

Summary of MNSs Antibody Characteristics

Antibody IgG Class Clinically significant

Anti-M IgM (rare IgG) No

Anti-N IgM No

Anti-S IgG Yes

Anti-s IgG Yes

Anti-U IgG Yes

Lutheran Blood Group System (ISBT 005)First example of anti-Lua was found in 1946.Two codominant alleles: Lua and Lub

Antigens are poorly developed at birth.

Lutheran AntigensGenotype Frequency

Lu(a+b=) 0.15%

Lu (a+b+) 7.5%

Lu (a=b+) 92.35%

Lu (a=b=) Very Rare

Anti-Lua

Uncommon, usually naturally occurring saline agglutinin.

Not clinically significantReacts at room temperatureRARE Mild HDNNaturally occurring or RARELY immune

stimulated.May agglutinate RBCs in-vitro in MF manner

which is a characteristic helpful in identifying.Donors do NOT need to be antigen typed, must

be crossmatch compatible.

Anti-Lub

Clinically significant IgG.Has caused MILD HDFN.Has been reported to cause diminished

survival of transfused RBCs (HTR).Rare because Lub is high incidence antigen.Finding compatible blood difficult, 99% of

population is positive.What are two potential sources of

compatible blood?Donors must be antigen negative AND

crossmatch compatible.

Systems that Produce Warm-Reacting Antibodies

Kell System (ISBT 006)K antigen first identified in 1946 as causative

antibody in case of HDFN.2 major alleles (over 20 exist)

K (Kell), <9% of populationk (cellano), >90% of population

The K and k genes are codominant alleles on chromosome 7 that code for the antigens

Well developed at birthThe K antigen is very immunogenic (2nd to

the D antigen) in stimulating antibody production

Kell antibodiesProduced as a result of immune stimulation.IgG (react well at AHG)Clinically significantAnti-K is most common because the K antigen is

extremely immunogenicCaused numerous cases of HTRs both immediate and

delayed.Cause of severe HDFN.

Anti-k occurs much less frequently due to high frequency of antigen, <1 in 500 people are k negative.

Donor units must be antigen negative, crossmatch compatible.

Other Kell System AntigensOther sets of alleles also exist in the Kell system.Kp antigens

Kpa (Penney, KEL3, 1957) low frequency antigen (only 2%)

Kpb (Rautenberg, KEL4, 1958) high frequency antigen (99.9%)

Js antigensJsa (Sutter, KEL6, 1958), 20% in Blacks, 0.1% in

WhitesJsb (Matthews, KEL7, 1963), is high frequency 80-100%

K is a null phenotype.McLeod

McLeod SyndromePhenotype has weakened expression of Kell

system antigensAssociated with structural and functional

abnormalities of RBCs and leukocytes. Causes abnormal red cell morphologies and

decreased red cell survival:Acanthocytes – spur cells (defected cell membrane)Reticulocytes – immature red cells

Associated with chronic granulomatous diseaseWBCs engulf microorganisms, but cannot kill (normal

flora)

Other Kell System AntibodiesSimilar serologic characteristics.Clinically significant, immune antibodies.Frequency of detection influenced by

ImmunogenicityDistribution of antigen in population.

Antibodies are rare which suggests low immunogenicity.

If antigen

Kidd Blood Group

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 rare

2 antigensJka and Jkb (codominant alleles)Show dosage

Kidd AntigensWell developed at birthEnhanced by enzymesNot very accessible on the RBC membrane

Kidd antibodiesAnti-Jka and Anti-Jkb

IgGClinically significantImplicated in HTR and HDNCommon cause of delayed HTRUsually appears with other antibodies when

detected

Kidd antibodiesAnti-Jk3

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

Duffy Blood Group

Phenotypes Blacks Whites

Fy(a+b-) 9 17

Fy(a+b+) 1 49

Fy(a-b+) 22 34

Fy(a-b-) 68 RARE

Predominant genes (codominant alleles):Fya and Fyb code for antigens that are well

developed at birthAntigens are destroyed by enzymesShow dosage

Duffy antibodiesIgGDo not bind complementClinically significant Stimulated by transfusion or pregnancy but

not a common cause of HDNDo not react with enzyme treated RBCs as

antigens are destroyed/denatured.

The Duffy and Malaria ConnectionMost African-Americans are Fy(a-b-)Certain malarial parasites (Plasmodium

knowlesi and P. vivax) cannot invade Fya and Fyb negative cells

Antigen acts as a receptor for invasion and 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…

Bg AntigensThree (Bennett-Goodspeed) Bg antigens:

Bga

Bgb

Bgc

Related to human leukocyte antigens (HLA) on RBCs

Antibodies are not clinically significant

Sda AntigensHigh incidence antigens found in tissues

and body fluidsAntibodies are not clinically significantAntibodies 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 women66% 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 AntigensHigh Titer Low Avidity (HTLA)Occur with high frequencyAntibodies are VERY weak and are not

clinically significantDo not cause HDN or HTR

Review

Cold AntibodiesIgMReact at RT or colderNO HDFN or HTRDonor units do not need to be phenotyped

for antigen.Donor units must be crossmatch

compatible.

Cold Antibodies (IgM)Anti-Lea

Anti-Leb

Anti-IAnti-P1Anti-MAnti-A, -B, -HAnti-N

LIiPMABHNNaturally Occurring

Cold Reacting Antibodies

Warm AntibodiesIgGReact at 37C and, most frequently, at AHGCause of HDFN and HTRDonor units must be phenotyped for

antigen and be antigen negative.Donor units must be crossmatch

compatible.

Warm antibodies (IgG)

Rh antibodiesKiddKell DuffyS,s

Warm Reacting Antibodies

Remember enzyme activity:

Enhanced by enzymes

Destroyed by enzymes

KiddRh

LewisIP

Fya and Fyb M, NS, 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

M&Ns

adapted from Clinical Laboratory Science Review: A Bottom Line Approach (3rd Edition)

M&Ns

Kidd Duffy Rh MNSs

ReferencesRenee Wilkins, PhD, MLS(ASCP)cm University

of Mississippi Medical CenterAABB Technical Manual, 16th edition, 2008Basic and Applied Concepts of

Immunohematology, 2nd edition, 2008