MIDTERM LECTURE L1: THE MNS SYSTEM Flashcards by Denzeline Go

MNS system ISBT

002

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Landsteiner and Levine found new antigen specificities by immunizing rabbits with

human RBCs

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Anti-M and anti-N were discovered from the rabbit sera in what year

1927

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T/F: M and N are antithetical antigens

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Who discovered S antigen

Walsh and Montgomery

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In what year was S antigen discovered

1947

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Antithetical partner of S antigen

s antigen

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s antigen was discovered in what year

1951

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There is equilibrium/disequilibrium(?) in the expression of S and s with M and N.

disequilibrium

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In white populations, what is the order of relative frequency for common MNS blood group system haplotypes? (MOST- LEAST frequent)

Ns > Ms > MS > NS

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In 1953, which scientist named an antibody to the high-prevalence antigen U?

Wiener

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U stands for

for almost UNIVERSAL distribution

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The inclusion of U into
the MNS system was due to the observations of which scientist

Greenwalt and colleagues

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What did Greenwalt and his colleagues observed?

All U– RBCs were also S–s–

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How many antigens have been included in the MNS system?

46 antigens

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MNS is almost equal in antigen size and complexity to what blood group system

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The genes encoding the MNS antigens are located on what chromosome?

chromosome 4

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The M and N antigens are found on a well-characterized
glycoprotein called

Glycophorin A (GPA)

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Major RBC sialic acid–rich glycoprotein (sialoglycoprotein, SGP)

Glycophorin A (GPA)

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The M and N antigens are antithetical and differ in their amino
acid residues at positions

1 and 5

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M amino acid at position 1

serine

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M amino acid at position 5

glycine

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N amino acid at position 1

leucine

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N amino acid at position 5

glutamic acid

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There are about how many copies of GPA per RBC

about 10^6 copies

T/F: MNS are not well developed at birth

F (they're well developed at birth)

T/F: M and N are located at the outer end of GPA

M and N are easily destroyed by what routine blood bank enzymes and less common enzymes?

routine blood bank enzymes - ficin - papain - bromelin less common enzymes - trypsin - pronase

Can MNS antigens be destroyed by DTT alone?

NO (needs ficin and papain) DTT + f + p = ZZAP

Cleaves sialic acid

neuraminidase

neuraminidase is also known as

neuraminic acid or NeuNAc

M and N antibodies are homogenous/heterogeneous(?)

heterogenous

M and N antigens are detected on what tissues

renal endothelium, and epithelium

S and s antigens are located on a smaller glycoprotein called

glycophorin B (GPB)

S and s are differentiated by the amino acid at what position on GPB?

position 29

Amino acid that defines S

methionine

Amino acid that defines s

threonine

How many copies of GPB per RBC

about 200,000

There are about how many times more copies of GPB on S+s– RBCs than on S–s+ RBCs?

1.5 times more copies

Are S and s well developed at birth?

Yes

T/F: S and s antigens are less easily degraded by enzymes because the antigens are located farther down the glycoprotein

S and s antigens have enzyme-sensitive sites that are less/more(?) accessible.

less

Enzymes that destroy S and s acitivity

- Ficin - papain - bromelin - pronase - chymotrypsin

T/F: Trypsin does not destroy the S and s antigens, and neither does DTT, AET, chloroquine, or glycine-acid EDTA treatment.

Is Anti-M naturally occurring?

yes

Anti-M is mostly what class of immunoglobulin?

IgG

Anti-M is how many percent of IgG

50-80%

Does Anti-M bind complement?

No, regardless of their immunoglobulin class

Does anti-M react with enzyme-treated RBCs?

Anti-M is more common in children/adult(?)

children

Anti-M is more common in patients with

bacterial infection and burns

Anti-M is pH dependent. What pH?

6.5

Anti-M lectin

Iberis amara

T/F: As long as anti-M reacts at 37°C, it is clinically significant for transfusion.

F (As long as anti-M doesn't react at 37°C, it is not clinically significant for transfusion and can be ignored)

Does anti-M often cause HTRs, decreased cell survival, and HDFN?

no (it RARELY)

Anti-N is cold/hot(?) reactive

cold

Anti-N immunoglobulin class

IgM and IgM

Is anti-N clinically significant?

No, not clinically significant

Does Anti-N bind complement?

No, it doesn't

Anti-N is seen in which patients

renal patients

What substance may alter the M and N antigens?

formaldehyde

Anti-N lectin

▪ Vicia graminea, ▪ Bauhinia variegate ▪ Bauhinia purpura

Anti-S and anti-s are mostly what immunoglobulin class?

Mostly IgG

Anti-S and anti-s are reactive at what temperature

37C

Can anti-S and anti-s bind to complement?

yes

A few of anti-S and anti-s express optimal reactivity between 10°C and 22°C by what test

saline indirect antiglobulin test

If anti-S or anti-s specificity is suspected but the pattern of reactivity is not clear, what can you do that can help in identification?

incubating tests at RT and immediately performing the antiglobulin test (without incubating at 37°C)

T/F: Dosage effect can be exhibited by many examples of anti-S and anti-s, but not as dramatic as seen with anti-M and anti-N

Only how many percent of whites are s–?

11% of whites

Only how many percent of blacks are s–?

3% of blacks

S– units/s- units(?) are much easier to find

S- units

How many percent of whites are S–?

45% of whites

How many percent of blacks are S–?

69% of blacks

phenotype with partial/complete deletion of GPB

U-phenotype (Universal)

U-phenotype (Universal) immunoglobulin class

IgG

Can U-phenotype (Universal) cause severe HTR and NDN?

yes

RBCs of individuals with U-phenotype type?

S-s-U-

phenotype with gene deletion of GPA

En (a-) phenotype (envelope)

rare and silent phenotype

Mk phenotype (null)

Mk phenotype was named by

Metaxas and Metaxas-Buhler

In what year did Metaxas and Metaxas-Buhler find an allele that does not produce M or N

1964

RBCs of individuals with Mk phenotype type?

M–N–S–s–U–En(a–)Wr(a–b–)

MNS phenotype common in blacks

U-phenotype

En (a-) phenotype is resistant to what infection

Pasmodium vivax

Who discovered En phenotype

Darnborough and cowrkers and Furuhjelm and colleagues

En(a-) phenotype was discovered in what year

1969

En(a–) individuals appeared to have RBCs typed as?

M–N– with reduced NeuNAc

Most En(a–) individuals produce what antibody

anti-En^a

What parasite appears to use alternative receptors, including GPA and GPB for cell invasion?

Plasmodium falciparum