Other Blood Group 1212

8/8/2019 Other Blood Group 1212

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Other Blood Group systemsM kasthuri bai


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Basic terms to remember

C linical significance : antibodies that areassociated with decreased R BC survival

Transfusion reactions HDN

Not clinically significant : antibodies that do notcause red cell destruction

C old reacting antibodies : agglutination bestobserved at or below room temp.Warm reacting antibodies : agglutination bestobserved at 37 C


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Other antigens

LewisIi

PMNSsKell

KiddDuffy

Lutheran


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Systems that Produce C old-Reacting Antibodies


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Lewis AntigensSoluble antigens produced by tissues andfound in body fluids (plasma)Adsorbed on the R BC

Legenes

Le substancein plasma

RBC

Lewis substanceadheres to RBC

becoming an antigen


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Lewis inheritanceLewis system depends on Hh , Se, and Le genesle, h , and se do not produce products

If the Le gene is inherited , Lea

substance is producedLe, H , and Se genes must ALL be inherited toconvert Le a to Le b. 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-)


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Lewis AntibodiesUsually occur naturally in those who are Le(a-b-)

IgM

May be detected soon after pregnancy because

pregnant women may temporarily becomeLe(a-b-)


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I antigensThese antigens may be I or iThey form on the precursor chain of R BC

Newborns have i antigenAdults have I antigen

i antigen (linear) converts to I (branched) asthe child matures (precursor chain is morelinear at birth) at about 18 months


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I antibodiesMost people have autoanti-I (RT or 4 C)

Alloanti-I is very rare

Cold-reacting (RT or below ) IgM antibody

Clinically insignificant


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P AntigenSimilar to the A BO system

The most common phenotypes are P1 and P2 P1 consists of P1 and P antigens P2 consists of only P antigens

75% of adults have P1


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P1 AntigenStrength of the antigen decreases uponstorageFound in secretions like plasma andhydatid cyst fluid C yst of a dog tapeworm


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P antibodiesAnti-P1 Naturally occurring IgM

Not clinically significant C old agglutinin

Anti-P Naturally occuring IgM Wide thermal range


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MNSs B lood SystemStrucrural protein of red cells4 important antigens (more exist): M N S s

M & N located on Glycophorin A

S & s and U located on GlycophorinB

Remember: Glycophorin is a protein that carriesmany R BC antigens


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MNSs Antigens

RBC

Glycophorin A

Glycophorin B

M

N

SsU

M & N only differ in

their amino acidsequence at positions1 and 5

S & s only differ intheir amino acid

sequence at position29

.5, 4, 3, 2, 1 (NH 2 end)COOH end ..


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MNSs antigensall show dosage

M & N give a stronger reaction whenhomozygous , (M+N-) or (M-N+)Weaker reactions occur when in the

heterozygous state (M+N+)


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Anti-M ,-N ,-S ,-s antibodiesAnti-M and anti-N IgM (rarely IgG)

C linically insignificant

Anti-S, and Anti-s C linically significant IgG C an cause R BC destruction and HDN Anti-s reacts at thermal but Anti-S at cold


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MNSs AntibodyC

haracteristicsAntibody IgG C lass C linicallysignificant

Anti-M IgM (rare IgG) No

Anti-N IgM No

Anti-S IgG Yes

Anti-s IgG Yes


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Systems that Produce Warm-Reacting Antibodies


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K ell SystemMembrane bound enzyme

2 major antigens (over 20 exist) K (K ell) , 90% of population

The K and k genes are codominant alleles on

chromosome 7 that code for the antigens

The K antigen is very immunogenic ( 2nd to the Dantigen) in stimulating antibody production


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K ell antibodies

IgG (react well at AHG)Produced as a result of immune stimulation(transfusion , pregnancy)C linically significantAnti-K is most common because the K antigen is extremely immunogenic


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K idd Antigens

Membrane transporters or channelsWell developed at birthNot very accessible on the R BC membrane


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K idd antibodies

Anti-Jk a and Anti-Jk b

IgG C linically significant Implicated in HTR and HDN C ommon cause of delayed HTR

Usually appears with other antibodies whendetected


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Duffy B lood GroupC hemokine receptors

Predominant genes (codominant alleles): F ya and F yb code for antigens that are well

developed at birth


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Duffy antibodiesIgG

C linically significantStimulated by transfusion or pregnancy (butnot a common cause of HDN)


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The Duffy and MalariaC onnection

Most African-Americans are Fy(a-b-)Interestingly , certain malarial parasites

( P la sm odiu m kn owle s i and P. v ivax ) will notinvade Fy a and Fy b negative cellsIt seems either Fy a or Fy b are needed for themerozoite to attach to the red cell

The Fy(a-b-) phenotype is found frequently inWest and C entral Africans , supporting the theoryof selective evolution


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LutheranB

lood Group SystemC ell adhesion molecules2 codominant alleles: Lua and Lub

Weakly expressed on cord blood cellsMost individuals (9 2%) have the Lu b

antigen , Lu(a-b+)The Lu(a-b-) phenotype is RARE


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Lutheran antibodiesAnti-Lu a IgM and IgG Not clinically significant

Reacts at room temperature Mild HDN Naturally occurring or immune stimulated

Anti-Lu b

Rare because Lu b

is high incidence antigen IgG Associated with transfusion reactions (rare HDN)


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Thank you

Other Blood Group 1212

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