Blood Groups: Lewis Antigens and Systems

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the genotype of an individual who is Leb positive?

Lele/SeSe

Sese/Sese

Lele/Lele

Lele/Sese (correct)

What is the frequency of the Le(a-b+) phenotype in the Black population?

55% (correct)

72%

22%

What is the characteristic of MN antigens that makes them useful in paternity testing?

They are found on glycophorin B

They are easily destroyed by enzymes

They are poorly developed at birth

They are codominant alleles (correct)

What is the amino acid residue at position 1 of the N antigen?

Leucine Signup and view all the answers

What is the characteristic of Lewis antibodies that makes them useful in identifying other antibodies in serum?

They can be neutralized using commercially prepared Lewis substance Signup and view all the answers

What is the effect of the interaction between the Le gene and the Se gene on the Lewis phenotype?

The Le gene and the Se gene interact to produce a unique phenotype Signup and view all the answers

What is the function of the Lewis gene (Le) in the Lewis blood group system?

Codes for the production of fucosyltransferase enzyme 1 Signup and view all the answers

How do erythrocytes acquire the Lewis phenotype?

By adsorbing Lewis substances from the plasma Signup and view all the answers

What is true about the Lewis antigen?

It is soluble and found in plasma and saliva Signup and view all the answers

What is the function of the Leb antigen?

It is the receptor for Helicobacter pylori Signup and view all the answers

What determines the secretor status?

The Se gene Signup and view all the answers

What is the genotype of an individual who does not produce any Lewis antigen?

lele Signup and view all the answers

What type of molecules are Lewis antigens found in secretions?

Glycoproteins Signup and view all the answers

What is the role of the H gene in the Lewis blood group system?

It produces the ability to secrete H antigen Signup and view all the answers

What is the effect of the lele genotype on Lewis antigen expression?

It does not produce any Lewis antigen Signup and view all the answers

What is the function of the fucosyltransferase enzyme?

It converts the precursor material to Lea substance Signup and view all the answers

What is the type of bacterium associated with gastritis and peptic ulcer disease that the Leb antigen is a receptor for?

Helicobacter pylori Signup and view all the answers

What is the characteristic of Lewis antigens that distinguishes them from other blood group antigens?

They are soluble and found in plasma and saliva Signup and view all the answers

What is the genotype of an individual who has both the Lea and Leb antigens on their red cells?

Lele/Lele Signup and view all the answers

What is the characteristic of the MN antigens that makes them susceptible to destruction?

They are easily destroyed or removed by enzymes Signup and view all the answers

What is the frequency of the Le(a-b-) phenotype in the White population?

6% Signup and view all the answers

What is the characteristic of the Lewis antibodies that makes them activate the complement?

They can cause in vivo and in vitro hemolysis Signup and view all the answers

What is the amino acid residue at position 5 of the M antigen?

Glycine Signup and view all the answers

What is the result of the interaction between the Le gene and the Se gene on the Lewis phenotype?

The Le gene and the Se gene are codominant Signup and view all the answers

On which chromosome are the GE antigens inherited?

Chromosome 2 Signup and view all the answers

Which of the following is a high-incidence antigen in the Gerbich Blood Group System?

Ge2 Signup and view all the answers

What is the name of the phenotype characterized by the absence of all GE antigens and a change in electrolyte morphology in the form of elliptocytosis?

Leach phenotype Signup and view all the answers

Which antigen is carried by decay accelerating factor (DAF) and is involved in the regulation of complement activation?

Cra Signup and view all the answers

What is the characteristic of anti-Ge2 and anti-Ge3 antibodies?

They are naturally occurring and can cause acute transfusion reactions Signup and view all the answers

Which of the following antigens is a low-incidence antigen in the Gerbich Blood Group System?

Wb Signup and view all the answers

What is the percentage of the general population that has the Yta high-incidence antigen?

99.8% Signup and view all the answers

On which protein is the Xga antigen carried?

A protein with cell adhesion properties Signup and view all the answers

What is the frequency of the Xg' antigen in females?

89% Signup and view all the answers

What is the characteristic of anti-Dia and anti-Dib antibodies?

IgG, red cell-stimulated Signup and view all the answers

What is the location of the gene that codes for the Xg allele?

Short arm of the X chromosome Signup and view all the answers

What is the characteristic of Sc-1, -2, -3 rare null phenotype?

Found in the Marshall Islands and New Guinea Signup and view all the answers

What is the function of the CD147 protein, which carries the OK blood group antigens?

Immune adhesion Signup and view all the answers

Which antigen is carried on the glycerol transporter aquaporin 3 (AQP3)?

GIL Signup and view all the answers

What is the characteristic of Anti-Vel antibodies?

IgG and causes in vitro hemolysis Signup and view all the answers

Which HLA antigen is detectable on RBCs?

HLA-B7 Signup and view all the answers

What is the feature of High-Incidence Antigens unrelated to Principal Blood Group Systems?

Occurring in 99.9% of the population Signup and view all the answers

What is the characteristic of Antibodies to High-Frequency Antigens?

Exhibiting high-titer, low-avidity reactivity Signup and view all the answers

What is the name of the antigen found on the hematopoietic isoform of the CD44 marker?

Ina Signup and view all the answers

Which antigen is found on the glycoprotein CD108?

JMH Signup and view all the answers

What is the function of the Rh-associated glycoprotein (RhAG)?

Essential for Rh antigen expression Signup and view all the answers

Which antigen is known to cause severe immediate HTRs and HDFN?

Ata Signup and view all the answers

Study Notes

Lewis Blood Group System

Individuals with at least one Le gene and one Se gene are Leb positive.
Lewis antigens are acquired by erythrocytes from plasma, not membrane-bound.
Lewis antigens exist as soluble glycoproteins (in secretions) and glycolipids (in plasma).
Anti-Lea and Anti-Leb antibodies are typically IgM and can activate complement leading to hemolysis.

Lewis Phenotypes and Frequencies

Le (a+b-) phenotype is found in 22% (Whites) and 23% (Blacks).
Le (a-b+) phenotype occurs in 72% (Whites) and 55% (Blacks).
Le (a-b-) phenotype is less common, at 6% (Whites) and 22% (Blacks).
Le (a+b+) phenotype is rare in both populations.

MNSs Blood Group System

MN antigens are present on glycophorin A and vary amino acid residues (M: serine and glycine; N: leucine and glutamate).
Both M and N antigens are codominant and easily destroyed by enzymes.
The system shows dosage effects relevant in paternity testing.

Gerbich Blood Group System

Composed of high incidence (Ge2, Ge3, Ge4) and low incidence (Wb, Lsa, Ana, Dha) antigens, expressed on glycophorins C and D.
Anti-Ge2 and Anti-Ge3 antibodies are naturally occurring and can cause transfusion reactions.

Cromer Blood Group System

High incidence antigens include Cra, Tca, Dra, and Esa.
Antibodies like anti-Wb and anti-Lsa are IgG and implicated in transfusion reactions but not in HDFN.

Diego Blood Group System

Dia antigens are significant in the study of Mongolian ancestry; located on anion exchange molecule (AE-1).
Both anti-Dia and anti-Dib are IgG and reactive in the indirect antiglobulin test.

Other Minor Blood Groups

Cartwright System: Antibodies (anti-Wra) are IgG, immune-stimulated, and react in testing.
Xg System: Xga antigen has a different frequency between sexes (89% females, 66% males).
Scianna System: Anti-Sc antibodies can cause transfusion reactions.

Clinical Relevance of Antibodies

High frequency antibodies (Anti-Ch, Anti-Rga) are generally clinically insignificant.
Anti-Vel can cause severe transfusion reactions.
Antibodies can be naturally occurring and vary in their reactivity.

High-Incidence vs Low-Incidence Antigens

High-incidence antigens manifest in over 99.9% of the population (e.g., Augustine, Vel).
Low-incidence antigens show less than 1% occurrence; examples include Wright (Swa) and By (Mta).

Antibody Characteristics

Clinically significant antibodies typically react in indirect testing.
Naturally occurring antibodies may be IgM, whereas immune-stimulated antibodies tend to be IgG.
Some antibodies bind complement and can cause hemolysis, while others are labile or enhance in response to infections.

Summary of Antibody Types

Warm antibodies: React at body temperature; significant in transfusions.
Cold antibodies: React at lower temperatures; can indicate certain conditions like infectious mononucleosis.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about the Lewis antigen system, its production, and characteristics. Understand how erythrocytes acquire the Lewis phenotype and the differences between Lewis antigens and other blood groups.