Blood Antigen Systems and Their Frequencies
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Questions and Answers

Which antigen systems are frequently documented on commercial red blood cells alongside ABO and Rh antigens?

  • K, k, Fya (correct)
  • I, Jka, S
  • A, B, O
  • K, M, L

What role do proteolytic enzymes play in antibody identification?

  • They solely identify Duffy and Kell antigens.
  • They remove structures from the red cell surface and expose others. (correct)
  • They eliminate the need for antibody testing.
  • They enhance reactivity of all antigens.

Which of the following antigen systems is unaffected by proteolytic enzymes?

  • Kell
  • Lewis
  • Kidd
  • Duffy (correct)

What is the typical class of antibodies produced against Lewis antigens?

<p>IgM (D)</p> Signup and view all the answers

Which enzyme is most commonly used to treat red blood cells for antibody identification?

<p>Ficin (A)</p> Signup and view all the answers

Which antigens are enhanced by enzymatic treatment according to the provided information?

<p>H and I (A)</p> Signup and view all the answers

What is the effect of reducing agents such as dithiothreitol (DTT) on Kell system antigens?

<p>They break disulfide bonds and destroy Kell system antigens. (A)</p> Signup and view all the answers

What is the significance of Lewis and I antigens in fetuses?

<p>They are absent on cells at birth. (D)</p> Signup and view all the answers

Which antigen is destroyed by enzymes among the listed options?

<p>Duffy (D)</p> Signup and view all the answers

What is produced by individuals with the null phenotype due to a double dose of the silent allele Ko?

<p>Anti-Ku (A)</p> Signup and view all the answers

Which condition is associated with the McLeod phenotype?

<p>Chronic granulomatous disease (CGD) (B)</p> Signup and view all the answers

What is the incidence of Jka+ antigen in the European population?

<p>77% (B)</p> Signup and view all the answers

Which antigen is part of the Kidd blood group system and is present alongside Jka and/or Jkb?

<p>Jk3 (D)</p> Signup and view all the answers

Which of the following antibodies is typically associated with Kidd system antigens?

<p>Anti-Jkb (D)</p> Signup and view all the answers

Which statement is true about the XK gene?

<p>It results in the production of the high-incidence antigen Kx. (C)</p> Signup and view all the answers

What is the typical immunoglobulin class of antibodies in the Kidd blood group system?

<p>IgG (B)</p> Signup and view all the answers

What is the significance of the K antigen in the Kell blood group system?

<p>It is the next most immunogenic antigen after D. (B)</p> Signup and view all the answers

Which antibodies are clinically significant in the context of the Kell blood group system?

<p>Anti-K may occasionally be IgM. (B), Anti-K and anti-k. (C)</p> Signup and view all the answers

What are the frequencies of K and k antigens in the European population?

<p>K has a frequency of about 9% and k is &gt;99%. (B)</p> Signup and view all the answers

Which statement about the Kell blood group antigens is true?

<p>They are coded for by the KEL gene located on chromosome 7. (D)</p> Signup and view all the answers

How do anti-I, anti-H, and anti-IH autoantibodies affect blood tests?

<p>They can interfere with alloantibody identification testing. (A)</p> Signup and view all the answers

What is the likelihood of IgG anti-K production following transfusion of K-positive red blood cells?

<p>IgG anti-K production occurs roughly 10% of the time. (B)</p> Signup and view all the answers

Which of the following is true regarding the antithetical pairs of the Kell system?

<p>Kpb and Jsb are high-incidence antigens. (A)</p> Signup and view all the answers

What bonds hold the structure of the Kell protein together?

<p>Disulfide bonds. (A)</p> Signup and view all the answers

What is the result of being homozygous for the silent JK gene?

<p>Phenotype as Jk(a–b–) (C)</p> Signup and view all the answers

Which antibodies are associated with severe HDFN?

<p>Anti-Jka and Anti-Jkb (C)</p> Signup and view all the answers

Why can anti-Jka antibodies lead to a rapid hemolytic transfusion reaction?

<p>They can drop below detectable levels and then rise rapidly. (D)</p> Signup and view all the answers

What is the frequency of the Fya antigen in the European population?

<p>Approximately 66% (B)</p> Signup and view all the answers

What happens to Duffy antigens upon the storage of red blood cells?

<p>They may weaken. (B)</p> Signup and view all the answers

Which reagent can assist in identifying a Kidd system antibody?

<p>Polyspecific AHG reagent (A)</p> Signup and view all the answers

Which statement about the Duffy blood group system is correct?

<p>Fya antigen is present at a higher frequency than Fyb antigen. (C)</p> Signup and view all the answers

What is a common clinical scenario involving anti-Jka antibodies?

<p>Delayed hemolytic transfusion reaction (D)</p> Signup and view all the answers

Flashcards

Kell Antigens

Antigen system (K, k) frequently tested in blood typing. Cells with these antigens may react with corresponding antibodies.

Enzyme Treatment of Blood Cells

Lab process using enzymes (ficin, papain, bromelin, trypsin) to modify red blood cell surfaces, exposing or hiding antigens. Enzymes help in antibody identification.

ABO/H blood groups

Antigen system, including ABO and related blood group antigens, that are destroyed by enzymatic treatment, so they do not react with corresponding antibodies

Duffy Antigens

Antigens (e.g. Fy, in the Duffy system) that are unaffected by enzyme treatment and reaction with antibodies remains.

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Lewis antigens (Lea, Leb)

Antigen system with varying frequencies (Lea: 22%, Leb: 72%), present on cells later in life and enhanced when treated with enzymes.

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Rh antigens

Antigen system that is enhanced by enzyme treatment, affecting reactions with corresponding antibodies.

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I and H Antigens

Antigen systems enhanced by enzyme treatment. Absence at birth.

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MNSs Antigens

Antigen system that is unaffected by enzymatic treatment; therefore maintains its reactivity with antibodies.

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P Antigen

Antigen system affected by enzyme treatment; therefore maintains its reactivity with antibodies.

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Kidd Antigens

Antigen system affected by enzyme treatment; therefore maintaining its reactivity with antibodies.

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Kell Blood Group System Antigens

A blood group system with over 30 antigens, but K and k are the most significant. They're located on a glycoprotein in the red blood cell membrane.

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K Antigen Clinical Significance

A K antigen on red blood cells can trigger a strong immune response leading to hemolytic transfusion reactions and HDFN.

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k Antigen Frequency

The k antigen is very common (over 99% of the population is k+).

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Kell Blood Group system and Enzymes

Antigens in the Kell system are not affected by enzymes.

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High-Incidence Antigens

Antigens present in most people, are not explicitly documented on antigrams but can interfere with antibody identification testing.

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Low-Incidence Antigens

Antigens not as widespread compared to high-incidence antigens.

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Clinical insignificance of IgM antibodies against certain antigens

IgM antibodies against specific antigens (except for Bombay anti-H) are not considered significant in clinical settings.

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Penny and Sutter Antigens

Antigen pairs (Kpa/Kpb; Jsa/Jsb) located on the Kell protein.

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Hemolytic Transfusion Reaction

A serious reaction to a blood transfusion in which the recipient's immune system attacks the donated blood cells, potentially causing severe complications.

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Hemolytic Disease of the Fetus and Newborn (HDFN)

A condition affecting a baby's red blood cells when maternal antibodies attack fetal red blood cells, leading to anemia and other complications.

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Reducing Agents (e.g., DTT, 2-ME)

Substances that break disulfide bonds and can destroy Kell antigens.

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Kell System

Blood group system whose antigens can be destroyed by reducing agents like DTT or 2-ME.

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Ficin

An enzyme that does NOT affect Kell system antigens.

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Ko Null Phenotype

A rare condition where individuals inherit two copies of a silent allele, resulting in a complete lack of Kell antigens.

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Anti-Ku

Antibody produced by individuals with the Ko null phenotype, reacting with all cells except other Ko cells.

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Kx Antigen

A high-incidence antigen produced by the XK gene on the X chromosome.

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McLeod Phenotype

A rare phenotype lacking Kx antigen and high-incidence Kell antigen (Km), often associated with CGD.

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Anti-KL

Antibody mixture of anti-Kx and anti-Km, produced by individuals with the McLeod phenotype.

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Kidd Blood Group System

Blood group system with antigens Jka, Jkb, and Jk3, partly responsible for red blood cell transport of urea.

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Jka, Jkb, Jk3

Antigens in the Kidd blood group system.

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Enzyme Treatment (e.g., ficin)

A lab technique that enhances expression of some blood group antigens, including Kidd.

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Silent JK gene

A rare gene, more common in Polynesian people, that causes a lack of the Jk3 antigen, resulting in Jk(a–b–) phenotype.

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Anti-Jka/Anti-Jkb

Antibodies that can cause severe delayed hemolytic transfusion reactions (HDFN) due to disappearing/reappearing quickly and causing strong complement activation and hemolysis.

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Delayed hemolytic transfusion reactions

Transfusion reactions that happen hours or days after the transfusion due to antibodies dropping below detectable levels, then causing a rapid rise in titer and severe hemolysis.

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Duffy blood group system

A blood group system with six antigens, primarily focusing on Fya and Fyb alleles; frequent in Europeans.

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Fya+/Fyb+

Common blood type in Europeans; 66% are Fya positive and 83% are Fyb positive.

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Duffy antigens at birth

Well-developed at birth, though observed weakened by cell storage.

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Study Notes

Other Antigen Systems

  • Manufacturers provide paper antigrams listing red blood cell antigen profiles for antibody identification.
  • Frequently documented antigens include ABO, Rh, K, k, Fya, Fyb, Jka, Jkb, Lea, Leb, P1, M, N, S, s, Lua, Lub, and Xga.
  • Enzymes (ficin, papain, bromelain, trypsin) can be used to treat red blood cells in the lab. This removes or exposes structures. Some antigens are destroyed by enzymes, others are enhanced.

Lewis, I and H Antigens

  • European frequency for Lea: 22%
  • European frequency for Leb: 72%
  • Some enzymes enhance Lea and Leb expression
  • Lea/Leb antigens are present on fetal cells
  • Antibodies against Lea and Leb are generally IgM.

Kell and Kx Blood Group Systems

  • K and k antigens are the most important in the Kell system.
  • K is less frequent (9%) than k (>99%).
  • Anti-K is a significant cause of hemolytic transfusion reactions and HDFN.
  • K antigen is the next most immunogenic antigen to antibody D.
  • Kx is a high-incidence antigen. XK and KEL genes are linked by disulfide bonds.
  • Individuals with McLeod phenotype lack Kx and Km.
  • The Kell structure has disulfide bonds, which can be broken by reducing agents (DTT, 2-ME).

Kidd Blood Group System

  • Jka and Jkb antigens are well expressed at birth.
  • Kidd antigens may be enhanced by enzyme treatment.
  • Common antigens in the Kidd system are Jka (77%), Jkb (51%), and Jk3 (high-incidence).
  • Anti-Jka or anti-Jkb can cause severe HDFN.

Duffy Blood Group System

  • Fya and Fyb are important allelic pairs in the Duffy system.
  • Fya is present in 66% of Europeans, and Fyb, in 83%.
  • Fya antigens are destroyed by enzyme treatment.
  • Duffy antibodies are IgG; they do not bind complement.
  • Anti-Fya can lead to severe HDFN; Anti-Fyb is less significant.
  • Duffy null phenotype (FY*0) is associated with increased resistance to malaria.

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Related Documents

Lecture 9 – Kell, Kidd and Duffy System PDF

Description

This quiz covers various blood antigen systems including the ABO, Rh, and Lewis antigen systems, as well as the Kell and Kx systems. It highlights the frequency of these antigens in European populations and discusses the impact of enzymes on antigen expression. Test your knowledge on the importance of these systems in blood transfusion and immunology.

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