Blood Group Antibodies Quiz
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Questions and Answers

What is the optimal temperature for Anti-U to react?

  • 22C
  • 37C (correct)
  • 4C
  • Room Temperature

Which of the following is NOT a characteristic of Anti-M and Anti-N antibodies?

  • Naturally occurring
  • Clinically significant (correct)
  • Shows dosage
  • Cold IgM

What is the clinical significance of Anti-U?

  • May cause mild anemia
  • Causes delayed hemolytic transfusion reaction
  • Associated with severe hemolytic transfusion reactions and HDFN (correct)
  • Usually asymptomatic

Which blood group system does the P1 antigen belong to?

<p>P1PK blood group system (D)</p> Signup and view all the answers

Which of these antigens is NOT found on more than 99% of the population?

<p>Lu(a) (C)</p> Signup and view all the answers

What is the role of the P antigen in the blood group system?

<p>Production of transferase which transforms Pk antigen (B)</p> Signup and view all the answers

How can P1 antigen expression be inhibited?

<p>By a rare dominant gene, <em>in(lu)</em> (D)</p> Signup and view all the answers

What is the class of antibody associated with Anti-P1?

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

What is the primary use of the Antiglobulin test?

<p>Detection of RBCs that were sensitized with non-agglutinating &quot;incomplete&quot; Ab, <em>IgG</em> Ab. (B)</p> Signup and view all the answers

Which of the following blood group antibodies is NOT typically associated with clinically significant reactions?

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

How are monoclonal AHG reagents produced?

<p>Fusion of myeloma cells with mouse spleen lymphocytes. (C)</p> Signup and view all the answers

What type of antibody does the Anti-Lub antibody belong to?

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

What is the main difference between polyspecific and monospecific AHG reagents?

<p>Polyspecific AHG reacts with both IgG and IgM antibodies, while monospecific AHG only reacts with IgG antibodies. (A)</p> Signup and view all the answers

Which of the following is NOT a clinically significant blood group antibody?

<p>Anti-P1 (A)</p> Signup and view all the answers

Which of the following antibody class is primarily responsible for causing hemolytic disease of the fetus and newborn (HDFN)?

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

Which of the following is a characteristic of monoclonal AHG reagents?

<p>They are specific for a single epitope of human globulins. (A)</p> Signup and view all the answers

How can autoantibodies be removed from a patient's serum?

<p>By using the patient's own red blood cells to adsorb the autoantibodies (D)</p> Signup and view all the answers

Which of the following is NOT a factor that influences the sensitivity of an antibody screening test?

<p>Type of red blood cell used in the test (C)</p> Signup and view all the answers

What is the principle behind the adsorption technique used to remove antibodies from serum?

<p>Using a specific antigen to bind and remove targeted antibodies from the serum (B)</p> Signup and view all the answers

Why is using human platelet concentrate particularly useful for adsorbing HLA-related blood group antibodies from serum?

<p>Platelets contain a high concentration of HLA antigens, allowing for efficient binding of HLA-related antibodies. (A)</p> Signup and view all the answers

A negative result on a 3-cell antibody screen indicates a 95% confidence rate that there are no clinically significant antibodies. What is the main limitation of this 3-cell screen?

<p>It cannot detect antibodies with low titers or antibodies against low-frequency antigens. (D)</p> Signup and view all the answers

Which of these is an advantage of using a monospecific AHG reagent?

<p>Higher titer than polyclonal sera. (A)</p> Signup and view all the answers

Which of the following is a disadvantage of using a polyspecific AHG reagent?

<p>Lower specificity. (B)</p> Signup and view all the answers

What is the main purpose of an indirect antiglobulin test (IAT)?

<p>To detect the presence of incomplete antibodies in a patient's serum. (A)</p> Signup and view all the answers

Which of the following is NOT a reason why a direct antiglobulin test (DAT) may be required?

<p>A patient who is undergoing a routine blood donation. (B)</p> Signup and view all the answers

Which of the following is a potential clinical situation in which an antigen-antibody complex could form in-vivo?

<p>A patient with a history of autoimmune hemolytic anemia. (D)</p> Signup and view all the answers

What is the principle behind the direct antiglobulin test (DAT)?

<p>To detect in-vivo sensitization of red blood cells with IgG and/or complement components. (B)</p> Signup and view all the answers

Why is it important to consider the patient's diagnosis, drug therapy, and recent transfusion history when interpreting a positive DAT?

<p>To determine the significance of the positive result and the appropriate next steps. (A)</p> Signup and view all the answers

What is the rationale for the use of LISS or albumin during the incubation phase of an IAT?

<p>To enhance antibody binding to red blood cells. (B)</p> Signup and view all the answers

Individuals with the Le(a+b-) phenotype have which genotype for the Se gene?

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

Which of the following ABO blood group antigens are present in the secretions of individuals with the Le(a-b+) phenotype?

<p>A, B, H, Leª, Leb (C)</p> Signup and view all the answers

The Lewis gene is closely linked to which other genes on chromosome 19?

<p><em>Se</em> and <em>H</em> (B)</p> Signup and view all the answers

What determines the presence of Leª antigen in secretions?

<p>The presence of the <em>Lewis</em> gene (C)</p> Signup and view all the answers

Which of the following accurately describes the phenotype of individuals with the Le(a-b-) phenotype?

<p>They have the <em>Secretor</em> gene but do not produce ABH antigens in their secretions (B)</p> Signup and view all the answers

Which of the following statements accurately describes individuals with the sese genotype?

<p>They do not produce ABH antigens in their secretions (C)</p> Signup and view all the answers

What is the primary difference between Le(a+b-) and Le(a-b+) individuals?

<p>Le(a+b-) individuals have the <em>Lewis</em> gene but not the <em>Secretor</em> gene, while Le(a-b+) individuals have both genes (C)</p> Signup and view all the answers

Which of the following phenotypes is characterized by the presence of both Leª and Leb antigens on RBCs?

<p>Le(a-b+) (B)</p> Signup and view all the answers

What characterizes the Lewis Blood Group System distinctively compared to other blood group systems?

<p>The antigens are found on Type 1 glycosphingolipids in the plasma. (D)</p> Signup and view all the answers

Which of the following are the three common phenotypes of the Lewis Blood Group System?

<p>Le(a+b-), Le(a-b+), and Le(a-b-) (C)</p> Signup and view all the answers

How are the Lewis antigens Leª (LE1) and Leb (LE2) produced?

<p>By the interaction of independent genes coding for fucosyltransferases. (B)</p> Signup and view all the answers

What role does the Se (secretor) gene play in the Lewis Blood Group System?

<p>It determines the presence of Lewis antigens in body secretions. (A)</p> Signup and view all the answers

In which chromosome is the Se gene located?

<p>Chromosome 19 (D)</p> Signup and view all the answers

What differentiates the enzymes produced by the Se and H genes?

<p>The <em>H</em> gene enzyme adds L-fucose to Type 2 precursor chains, whereas the <em>Se</em> enzyme adds it to Type 1 precursor chains. (B)</p> Signup and view all the answers

How are the Lewis antigens like Leª (LE1) and Leb (LE2) eluted from red blood cells?

<p>They are extracted by increasing peripheral blood volume and lipoproteins. (C)</p> Signup and view all the answers

What type of sugars do fucosyltransferases transfer, relevant to the Lewis Blood Group System?

<p>L-fucose (D)</p> Signup and view all the answers

Flashcards

What makes the Lewis Blood Group system unique?

The Lewis blood group system is unique because it doesn't involve red blood cells directly producing its antigens. Instead, antigens are found on glycosphingolipids in plasma and passively adsorbed onto the red blood cell membrane.

What are the two main antigens in the Lewis Blood Group system?

The Lewis Blood Group System has two main antigens: Leª (LE1) and Leb (LE2).

What are the common phenotypes of the Lewis Blood Group system?

The Lewis Blood Group System has three common phenotypes: Le(a+b-), Le(a-b+), and Le(a-b-).

Are Leª (LE1) and Leb (LE2) antithetical antigens?

While initially thought to be antithetical, Leª (LE1) and Leb (LE2) are not opposite antigens. They are produced by different enzymes, not alternative alleles of the same gene.

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How are Leª (LE1) and Leb (LE2) encoded?

Leª (LE1) and Leb (LE2) are determined by the interaction of two fucosyltransferases, encoded by independent genes called Le and Se.

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What is a fucosyltransferase?

A fucosyltransferase is an enzyme that transfers an L-fucose sugar from a donor molecule (GDP-fucose) to an acceptor substrate.

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What are Lewis antigens and how are they acquired?

Lewis antigens are glycolipids, meaning they're made of sugars and fats. They are acquired by adsorption onto red blood cells from the surrounding plasma.

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What makes Lewis blood group antigens unique from other systems?

Lewis antigens are unique because they are not manufactured by the red blood cell itself. This makes them different from other blood group systems.

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What genotypes are referred to as secretors?

Individuals with either homozygous SeSe or heterozygous Sese genotypes.

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What genotype are non-secretors?

Individuals with only the se gene (homozygous sese).

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What are in sese individuals' secretions?

They fail to produce ABH Ag in their secretions.

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Where is the Lewis gene and what genes is it closely linked to?

The Lewis gene (LE or FUT3) is closely linked to the Se (FUT2) and H (FUT1) genes, all located on chromosome 19.

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How is the Le(a+b-) phenotype produced?

This phenotype results from inheriting the Lewis gene (LE or FUT3) but not the Secretor gene (SE or FUT2).

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How is the Le(a-b+) phenotype produced?

This phenotype is produced by inheriting both the Lewis (Le) gene and the Secretor (Se) genes. Both Le, H, and Se genes are present.

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How is the Le(a-b-) phenotype produced?

This phenotype is caused by not inheriting the Lewis gene (lele).

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What is in Le(a+b+) individuals' secretions?

This phenotype has no significant clinical relevance.

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Anti-U

An antibody that reacts with the cells of most people. It is an IgG antibody that reacts optimally at 37°C. It does not bind complement but can cause severe hemolytic transfusion reactions and HDFN.

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Anti-M and Anti-N

A naturally occurring, cold IgM antibody showing dosage. It is considered clinically insignificant.

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Anti-S, Anti-s, and Anti-U

A warm IgG antibody that requires exposure and shows minimal dosage. It is clinically significant.

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P1PK Blood Group System

A blood group system that includes the antigens P1 and Pk.

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Globoside Blood Group System

A blood group system that includes the antigen P.

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P1 Antigen

A high-incidence antigen found on more than 99% of the population. It is synthesized by glycosyltransferases and found on lymphocytes, monocytes, granulocytes, and RBCs.

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P1 Blood Group System

A blood group system that includes the P1 antigen and is considered to be part of the P1PK blood group system. (003)

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Anti-P1

An IgM antibody that reacts with the P antigen.

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Ab screening test

A blood test that screens for the presence of antibodies (Ab) in a patient's serum.

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Ab screening test accuracy

The Ab screening test is highly reliable, indicating a 95% chance of no clinically significant Ab if all 3 cells are negative.

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Ab screening test limitations

The Ab screening test cannot detect Ab that are below the sensitivity threshold or target low-frequency antigens.

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Adsorption

The process of removing specific Ab from the serum using known antigens (Ag) to isolate and identify the Ab by removing interfering Ab.

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How is adsorption performed?

In adsorption, a known Ag is added to the serum, allowing the Ab to bind to the Ag. The Ag-Ab complex is then removed by centrifugation, isolating the specific Ab of interest.

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What are AHG's used to detect?

Antibodies that bind to red blood cell antigens (RBC Ags) and do not cause direct agglutination.

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What does the antiglobulin test use?

A secondary antibody that attaches to and agglutinates sensitized red cells. This antibody is made in another species and is directed against human globulins.

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Where are AHG's obtained from?

Immunized non-human species are used to bind to human globulins. These globulins can be either free in serum or attached to Ags on RBCs.

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What are polyclonal AHG directed against?

These antibodies are directed against multiple epitopes. They are produced by injecting animals with human globulin components and then collecting the antihuman antibodies.

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How is monoclonal AHG produced?

Hybridoma technology fuses mouse spleen lymphocytes with myeloma cells.

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What are the practical uses of the Antiglobulin test?

This is a technique used to detect RBCs that were sensitized with non-agglutinating "incomplete" Ab, IgG Ab.

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How is AHG sera divided?

AHG sera is divided into two classes: monoclonal and polyclonal.

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What do monoclonal AHG produce?

An immortal cell line produces a specific antibody directed against a single epitope.

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Rabbit monoclonal IgG

Monoclonal antibodies that are specific for the IgG heavy chain, used for blood typing and other serological tests.

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Polyspecific AHG

A type of antibody reagent that recognizes multiple specificities on red blood cells, providing a broader detection range.

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Monospecific AHG

A type of antibody reagent that only recognizes a single specificity, such as the IgG heavy chain.

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Indirect Antiglobulin Test (IAT)

Used to detect the presence of antibodies that are attached to red blood cells but don't cause a visible agglutination reaction.

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What is the principle of IAT testing?

To detect in-vitro sensitized red cells.

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Direct Antiglobulin Test (DAT)

Used to detect the presence of antibodies that are already attached to red blood cells in vivo, meaning they have formed within the body.

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What is the principle of DAT testing?

To detect in-vivo sensitized red cells with IgG and complement components in which RBCs are mixed with antihuman globulin to determine if sensitization has occurred in vivo.

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What does interpreting the significance of a positive DAT require?

The knowledge of the pt’s diagnosis, drug therapy, and recent transfusion therapy.

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Study Notes

Lewis Blood Group System

  • The Lewis blood group system is unique because its antigens are not synthesized by red blood cells (RBCs). Instead, they are adsorbed onto the RBC membrane from the plasma.
  • The two main antigens in the Lewis blood group system are Leª and Leb.
  • The three common phenotypes of the Lewis blood group system are Le(a+b-), Le(a-b+), and Le(a-b-).
  • Leª and Leb antigens are not antithetical (opposite).
  • These antigens are encoded by two fucosyltransferase genes, Le and Se, which are independent genes.
  • Fucosyltransferases are enzymes that transfer an L-fucose sugar from a donor substrate to an acceptor substrate.
  • Lewis antigens are glycolipids acquired by adsorption from the surrounding plasma onto RBCs.
  • They are not manufactured by the red blood cell.

Lewis Phenotypes in Secretions and Se

  • The three Lewis phenotypes represent the presence or absence of Lewis and secretor enzymes.
  • The secretor (Se) gene is located on chromosome 19.
  • The two alleles at the chromosome 19 locus are Se and se.
  • The se allele is an amorph, producing no detectable product in secretions.

Enzyme Production by Se and H Genes

  • The enzymes produced by the Se and H genes are fucosyltransferases, but their functions differ.
  • The H-gene enzyme adds L-fucose to Type 2 precursor chains on RBC membranes.
  • The Se-gene enzyme adds L-fucose to Type 1 precursor chains, which are found in bodily fluids.
  • Individuals with the secretor genotype (SeSe or Sese) are secretors, while individuals with the non-secretor genotype (sese) are non-secretors.
  • Non-secretors lack ABH antigens in their secretions.

Lewis Phenotypes

  • Le(a+b-): This phenotype is produced by inheriting the Lewis gene (LE or FUT3) but not the secretor gene (SE or FUT2). Le and H antigens are produced when Le and H genes are present. The genotype is sese. It is a non-secretor of A,B,H antigens.
  • Le(a-b+): This phenotype is produced by inheriting both the Lewis gene (LE or FUT3) and the secretor gene (SE or FUT2). Le, H, and Se genes are present. A, B, H and Leb (LE2) antigens are produced.
  • Le(a-b-): This phenotype is caused by not inheriting the Lewis gene (lele). Le(a-b-) secretors have the Se gene and produce A, B, H and Leb (LE2) antigens in their secretions. Le(a-b-) non-secretors have no antigens in their secretions.

Development and Changes of Lewis Antigens after Birth

  • Lewis antigens are not fully developed at birth, but appear shortly thereafter as they are adsorbed onto the red blood cells.
  • The phenotype of cord blood and newborns is Le(a-b-).
  • Individuals with Le and sese genotypes do not have detectable Lewis antigens on cord cells, but secrete Leª in their saliva.

MNS Blood Group System

  • The genes of the MNS BGS are GYPA and GYPB.
  • The phenotypes of the MNS BGS are M+N-, M+N+, M-N+, and M-N-.
  • The S and s antigens are distinct from M and N antigens, but are genetically linked.

Anti-M and Anti-N

  • Anti-M is a cold antibody (optimally reactive at 4°C), and is rarely clinically significant.
  • Anti-N is a cold antibody and is rarely clinically significant.

Other Antigens

  • Anti-S, anti-s, and anti-U are uncommon, usually IgG antibodies, and are optimally reactive at 37°C.
  • Anti-U is commonly found in the serum of prenatal patients.
  • The various antigens, such as Lea, Leb, K, k, and so on are elaborated in their specific sections.

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Description

Test your knowledge on blood group antibodies with this comprehensive quiz. Explore key concepts such as the characteristics of Anti-U, Anti-M, and Anti-N antibodies, as well as the clinical significance of various antigens. Perfect for medical students and professionals in immunohematology.

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