MLSP 5513: Other Blood Groups Part 3

The alleles of the Kidd system

-Jka

-Jkb

-Jk3

-Jk (silent allele)

The antigens of the Kidd system

-Jka

-Jkb

-Jk3

Which Kidd phenotype is common in the white population

Jk(a+b+)

Which Kidd phenotype is common in the black population

Jk(a+b-)

Which Kidd phenotype is common in the asian population

Jk(a+b+)

Kidd antigens are encoded by

SLC14A1 gene on chromosome 18

How many times does the Kidd glycoproteins cross the RBC membrane

10x times

Jka and Jkb are expressed in a

codominant fashion

Jk3 is high frequency antigen present in

either Jka and/or Jkb individuals

What is responsible for the Jknull phenotype

-may be homozygous for silent Jk gene

-do not produce anti-Jk3

Kidd antigens characteristics

-not on other blood cells

-well developed at birth (7-11 weeks gestation)

-not destroyed by enzymes or disulfide reducers

-not strong immunogens

What are the primary Kidd antibodies

-anti-Jka

-anti-Jkb

Primary Kidd antibodies characteristics

-agglutination reactions show dosage

-cause hemolytic transfusion reactions

-antibody titer quickly fall

-clinically significant

Which Kidd system antibody is more common

Anti-Jka

Kidd antibodies are

IgG

-often require the AHG phase of testing

-bind complent

Kidd antibodies reactivity enhanced with

LISS and PEG

Function of Kidd antigens

RBC urea transporter

What is the most important antigens in the Duffy system

-Anti-Fya

-Anti-Fyb

Which duffy phenotype is common in the white population

Fy(a+b+)

Which Duffy phenotype is common in the black population

Fy(a-b-)

Which Duffy phenotype is common in the chinese population

Fy(a+b-)

The Duffy system is encoded by

DARC

-chromosome 1

Duffy system: alleles

-Fya

-Fyb

-Fy (silent allele)

The rare Fx phenotype is the result from

mutation of Fyb allele

Which are the co-dominant alleles of the Duffy system

Fya and Fyb

Duffy system: antigens characteristics

-glycoproteins traverses red cell membrane x7

-on endothelial and epithelial cells

-act as chemokine receptors

-well developed at birth

Do Fy(a-b-) individuals have adverse effects from a lack of Duffy antigens

no

Fy(a-b-) inheritance of

two Fy (silent alleles)

Fy(a-b-) RBCs are resistant to

P. knowlesi and P. vivax

Whicih Duffy system antibodies are not common antibodies

-anti-Fya

-anti-Fyb

Duffy system: antibodies characteristics

-poor immunogens

-most are IgG and require AHG test

-occasionally bind complement

-enhanced by LISS

-reactivity decreased or destroyed by enzymes

The development of anti-Fya and Fyb requires

prior sensitization by Duffy antigens

Anti-Fya and anti-Fyb characteristics

-clinically significant

-must transfuse antigen negative units

-rare autoantibodies

What genes are responsible for expression of MN and SsU blood group antigens

GYPA (MN) and GYPB (SsU)

Glycophorin A (GYPA) carries

MN antigens

Glycophorin B (GYPB) carries

Ssu antigens

Glycophorin null phenotype

MkMk lacks both MN and SsU antigens

Which MNSU system phenotype is common in the white population

M+N+

S-s+

Which MNSU system phenotype is common in the black population

M+N+

S-s+

The glycophorins of the MNSU system are described as

sialoglycoproteins

-rich in sialic acid

M and N antigens are destroyed by

enzymes including ficin, papain, trypsin, pronase and bromelain

M and N are well developed at

birth

Ss are variably sensitive to

ficin and papain

-close proximity to red cell surfaces make enzymatic cleavage diffiicult

S and s antigens are well developed at

birth

Which gene is responsible for the expression the U antigen

GYPB gene

U antigen: frequency

high frequency (99%)

deletions in GYPB may result in the

S-s-U or Uvar phenotype

-1.5% black individuals

-can make anti-U

Anti-M and - N characteristics

-naturally occurring IgM

-do not bind complement

-agglutination reaction may exhibit dosage

Anti-Ena

IgG antibodies against M and N antigens and may cause HTR and HDFN

How might the agglutination by anti-M be enhanced

incubating reaction in low pH solution

Anti-S and anti-s characteristics

-IgG antibodies

-may bind complement

-react best at 37C at AHG

-implicated in severe HDFN and HTF

-recipients must receive antigen-negative blood

Anti-U characteristics

-IgG antibodies

-clinically significant

-autoantibodies associated with warm autoimmune hemolytic anemia

GPA antigen may be receptor for

some E. coli strains that infect the urinary tract

GPA and GPB antigens may serve as

receptors for Plasmodium falciparum

Lutheran system is encoded by

BCAM on chromosome 19

BCAM encodes

a glycoprotein whose RNA is alternatively spliced resulting in either the longer Lu glycoprotein or the shorter basal cell adhesion molecule

Lutheran antigens belong to the

immunoglobulin supergene family

Lua and Lub are considered

clinically significant

Lua encodes the

low frequency antigen

Lub encodes the

high frequency antigen

How well are the Lua and Lub encoded at birth

poorly

-some glycoproteins are expressed on placental tissue and may absorb antibody to prevent transfer

What is the most common phenotype of Lutheran system

Lu (a-b+)

Lu(a-b-) phenotype may be the result of

-dominant inheritance of inhibitor gene In(Lu)

-silent Lu (amorp) in homozygous state

Silent Lu (amorph) can make

anti-Lu3

What are the common Lu antibodies

anti-Lua and Lub

Lu antibodies characteristics

-serologic problems uncommon due to antigens being poor immunogens, poorly developed at birth

Anti-Lua antibodies

-show saline and room temp reactivity

-may be naturally occuring

-may have IgA, IgG, and IgM forms

-most clinically insignificant

Anti-Lub antibodies

-most IgG

-react best at 37C during the AHG phase

-may be clinically significant

Anti-Lu3 reacts with

epitope present on both the Lua and Lub antigens

Anti-Lu3

-homozygous for the amorphic Lu gene

-AHG reactive, clinically significant

-can only receive Lu(a-b-) blood