Learn: Blood Typing (Kidd, Duffy, MNSs)

"When were M and N discovered and by whom?"

In 1927 by Landsteiner and Levine while immunizing rabbits.

When were S and s discovered?

"In 1947, after implementation of antiglobulin testing."

What did family studies show about MNS antigens?

"M, N, and S/s are closely linked."

Where are the MNS genes located?

On chromosome 4.

What MNS haplotype order is listed in the presentation?

Ns > Ms > MS > NS.

How many MNS antigens have been described?

46.

Which glycoprotein carries M and N antigens?

Glycophorin A (GPA).

Which glycoprotein carries S and s antigens?

Glycophorin B (GPB).

Which parasite can use glycophorins associated with the MNS system?

Plasmodium falciparum.

What does the presentation note about GPB and the N antigen?

Glycophorin B has an 'N' antigen and is expressed on cord cells.

How are MNS antigens affected by enzymes?

MNS antigens are destroyed by enzymes.

What role does dosage play in MNS antibody activity?

"Dosage plays a large role, especially for anti-M and anti-N."

What is the typical immunoglobulin class of anti-M and anti-N?

"Typically IgM, although many cases show IgG."

At what temperatures do anti-M and anti-N tend to react?

Cooler temperatures.

When are anti-M and anti-N typically considered insignificant according to the presentation?

Especially when they do not react at 37°C or are not IgG.

What is the typical immunoglobulin class and significance of anti-S and anti-s?

Typically IgG and usually clinically significant.

What association does the presentation give for anti-M?

It may appear with bacterial infections and can occur naturally.

"What pH does anti-M prefer?"

"A lower pH, around 6.5."

What is anti-Nf associated with?

Exposure to formaldehyde; it was common in dialysis patients.

"Why is true anti-N rare"

Because an 'N' antigen is present on glycophorin B.

What does En(a) stand for?

Envelope.

On which red cells is En(a) found?

On all red cells that have M or N.

What is the phenotype of En(a)-negative individuals?

"M−N−, typically due to deletion of GPA."

What is the clinical relevance of anti-En(a)?

It is an unexpected antibody.

What are the approximate population frequencies of S and s?

S: 50%; s: 90%.

What does the U antigen refer to in the MNS system?

'U' stands for universal.

What is the typical relationship between S/s and U?

Cells that are S−s− are typically U−.

In which populations is the U-negative phenotype found almost exclusively?

Populations of African descent.

Why is anti-U clinically important?

It is clinically significant and can cause hemolytic transfusion reactions (HTR) and HDFN.

What is the MkMk phenotype?

A null phenotype caused by complete deletion of GPA and GPB; cells are M−N−S−s−.

What antibodies may a person with the MkMk phenotype make?

They can make all associated MNS antibodies.

Does the presentation note hematologic differences in MkMk red cells?

No; it says there are no hematologic differences on the red cells.

What is Mur and why is it notable?

A GPB mutation common in Southeast Asia (about 9%) and highly immunogenic in some Asian countries.

What clinical reactions can anti-Mur cause?

Hemolytic transfusion reactions and HDFN.

How was the Kidd antibody system first reported?

"In 1951, Allen and colleagues reported an antibody in Mrs. Kidd's serum after her infant had HDFN."

Where are the Kidd genes located?

On chromosome 18.

How are Jka and Jkb inherited?

They are codominant.

What is the function of the Kidd protein?

It is a urea transporter.

Are Kidd antigens expressed on cord cells?

Yes.

"What happens to most red cells exposed to 2 M urea for one minute and how do Jka−Jkb− cells differ?"

Most red cells lyse in one minute; Jka−Jkb− cells take about 30 minutes to lyse.

What is the ISBT number for Kidd?

ISBT 009.

What are the typical features of Kidd antibodies?

IgG; show dosage; enhanced by enzymes; may be associated with intravascular hemolysis; and can fade in vivo.

What transfusion reaction are Kidd antibodies commonly linked to?

Delayed hemolytic transfusion reactions.

Why can Kidd antibodies be difficult to detect?

They can fade in vivo and may appear with other antibodies.

What testing consideration is noted for Kidd antibodies?

They may show enhanced results with serum and can fix complement well; polyclonal antisera (anti-IgG and anti-C3) may be needed.

What is an important practice when evaluating possible Kidd antibodies?

Always check the patient's transfusion and antibody history.

What is the Jk3 phenotype?

A null phenotype in which both Jka and Jkb are absent.

What antibody can a person lacking both Jka and Jkb make?

Anti-Jk3.

"In which population is the Kidd null phenotype most common"

Polynesian populations.

Where is the Duffy system located genetically?

On chromosome 1.

How are Fya and Fyb inherited?

Codominantly.

What is the Duffy protein's function?

"It is a chemokine receptor, ACKR1, previously known as DARC."

Which malaria parasite uses Duffy to enter red blood cells?

Plasmodium vivax.

Where is the Duffy protein found?

On red blood cells and tissues throughout the body.

What are the typical features of Duffy antibodies?

IgG; show dosage; are found on cord cells; can cause HTR and HDFN; and often appear with other antibodies.

How are Fya and Fyb affected by enzymes?

They are destroyed by enzymes.

What does the Duffy GATA-box mutation do to red-cell antigens?

It suppresses all Fy antigens on red blood cells.

"In which population does the presentation say the GATA-box mutation is found and at what frequency?"

People of African ancestry; approximately 67%.

What does the presentation note about Fyb with the GATA-box mutation?

Fyb remains present on tissues.

What is the stated relationship between the Duffy GATA-box mutation and P. vivax?

The mutation affects red-cell Duffy expression and is discussed in relation to response to P. vivax.

Which antibodies may be made by individuals with a non-GATA-box mutation who are Fya−Fyb−?

"Anti-Fy3, anti-Fy5, and anti-Fy6."

"How do anti-Fy3 anti-Fy5 and anti-Fy6 react"

They react with Fya or Fyb.

Which Duffy antigens are resistant to enzyme treatment?

Fy3 and Fy5.

What is absent on Rh-null cells among the Duffy antigens discussed?

Fy5.