BB - General Principles + Carbohydrate vs Protein Antigens + Inheritance + ABO Basics

How many blood group systems are currently recognized?

38 systems

How many provisional blood group systems are listed?

1 provisional

How many unique antigens are defined by recognized and provisional blood group systems?

326 antigens

What is the provisional blood group system called?

CTL2

What does CTL2 stand for?

Choline transporter

On which chromosome is the CTL2 blood group system coded?

Chromosome 19

Why is the CTL2 blood group system still considered provisional?

Unresolved genetics

Each blood group system is controlled by what kind of genetic basis?

Single gene

A blood group system may also be controlled by what type of gene relationship?

Linked homologs

Blood group systems demonstrate what within that system?

Antigens

Most blood group antigens are what general type of molecules?

Glycoproteins

The specificity of some blood group antigens is determined by what in carbohydrate antigens?

Carbohydrate epitopes

The specificity of some blood group antigens is determined by what in protein antigens?

Amino acids

Antigens within a blood group system are described as what?

Polymorphic

Blood group antigen differences usually arise from what type of genetic change?

SNP

A single nucleotide polymorphism may encode what kind of molecular change?

Acid substitution

A SNP may affect either a glycosyltransferase or what part of a red cell membrane protein?

Extracellular domain

Which general class of blood group antigens includes ABO, H, Lewis, I, P1PK, and Glob?

Carbohydrate antigens

Which general class of blood group antigens includes Duffy, Kidd, Kell, Rh, and MNS?

Protein antigens

Antibodies to carbohydrate antigens are often described as what in origin?

Naturally occurring

Antibodies to protein antigens are usually produced after what kind of event?

Antigen exposure

Antibodies to carbohydrate antigens are usually what immunoglobulin class?

IgM

ABO antibodies may be unusual because they can also be what classes besides IgM?

IgG, IgA

Antibodies to protein antigens are usually what immunoglobulin class?

IgG

Antibodies to carbohydrate antigens react best at what general temperature?

Room temperature

Antibodies to protein antigens react best at what temperature?

37°C

Because carbohydrate antibodies are usually IgM, they usually cause what visible reaction?

Direct agglutination

Some carbohydrate antibodies may initiate what immunologic cascade on red cells?

Complement activation

If AHG reagent contains anti-C3, what kind of surface event can be detected on red cells?

Complement coating

Which complement component is specifically noted as deposited on red cell surfaces?

C3b

Why is polyspecific antiglobulin useful in these situations?

IgG C3b

Antibodies to protein antigens usually attach to antigens but fail to show what visible reaction immediately?

Agglutination

Why do many IgG antibodies fail to show visible agglutination without AHG reagent?

Low valence

What reagent is often needed to visualize IgG-coated red cells?

Antiglobulin reagent

Blood group inheritance follows what broad genetic principles?

Mendelian principles

In inheritance, only how many members of an allelic pair are transferred to offspring?

One member

Most blood group antigens are expressed as what two major inheritance patterns?

Dominant, codominant

Some blood group system genes may also be expressed as what inheritance pattern?

Recessive

What ABO genotype is used as an example of heterozygous A?

AO

What ABO genotype is used as an example of heterozygous B?

BO

What ABO genotype is used as the example of codominant inheritance?

AB

What ABO genotype is used as the example of autosomal recessive inheritance?

OO

Which blood group system is the X-linked system?

Xg

A homozygous Xg female passes the Xg trait to what proportion of offspring?

All offspring

A heterozygous Xg female passes the Xg trait to what proportion of offspring?

50 percent

A hemizygous Xg male passes the Xg trait to which children?

All daughters

Which blood group system is considered the most important?

ABO system

Why is the ABO system considered the most important?

Expected antibodies

Individuals routinely demonstrate ABO antibodies in their serum to the ABO antigen they what?

Lack

ABO antibodies occur without prior exposure to what?

RBCs

ABO antibodies likely result from exposure to what kind of organisms?

Bacteria

The ABO locus is found on which chromosome?

Chromosome 9

ABO inheritance follows what kind of genetics?

Mendelian genetics

ABO phenotype prevalence varies by what factor?

Ethnicity

What is the prevalence of group O in White individuals?

45%

What is the prevalence of group O in Black individuals?

49%

What is the prevalence of group O in Hispanic individuals?

56%

What is the prevalence of group O in Asian individuals?

40%

What is the prevalence of group A in White individuals?

40%

What is the prevalence of group A in Black individuals?

27%

What is the prevalence of group A in Hispanic individuals?

31%

What is the prevalence of group A in Asian individuals?

28%

What is the prevalence of group B in White individuals?

11%

What is the prevalence of group B in Black individuals?

20%

What is the prevalence of group B in Hispanic individuals?

10%

What is the prevalence of group B in Asian individuals?

25%

What is the prevalence of group AB in White individuals?

4%

What is the prevalence of group AB in Black individuals?

4%.

What is the prevalence of group AB in Hispanic individuals?

3%.

What is the prevalence of group AB in Asian individuals?

7%.

The H, A, and B genes produce what type of enzymes?

Glycosyltransferases

These glycosyltransferase enzymes add immunodominant sugars to what kind of substances?

Precursors

The added sugars give rise to which three major antigens?

A, B, H

Which oligosaccharide chain has a beta 1-3 linkage?

Type 1

Which oligosaccharide chain has a beta 1-4 linkage?

Type 2

Type 1 oligosaccharide chains are mainly found where?

Secretions

Type 2 oligosaccharide chains are mainly found where?

RBCs

Type 1 oligosaccharide chains are mainly associated with what kind of molecules?

Glycoproteins

Type 2 oligosaccharide chains are associated with what three kinds of molecules?

Glycolipids, glycoproteins, glycosphingolipids

Which gene produces alpha 2 L-fucosyltransferase?

H gene

What immunodominant sugar is added by the H gene product?

Fucose

Which gene produces alpha 3 N-acetylgalactosaminyltransferase?

A gene

What immunodominant sugar is added by the A gene product?

N-acetylgalactosamine

Which gene produces alpha 3 D-galactosyltransferase?

B gene

What immunodominant sugar is added by the B gene product?

D-galactose

What glycosyltransferase activity is produced by the O gene?

None

What immunodominant sugar is produced by the O gene?

None

Which two ABO subgroups are described as the most widely recognized?

A1, A2

What reagent is used to differentiate A1 from A2?

Anti-A1 lectin

What plant source of anti-A1 lectin is listed?

Dolichus biflorus

What percentage of A individuals are A1?

80%.

What percentage of A individuals are A2?

20%.

What percentage of A2 individuals demonstrate anti-A1 in their serum?

5%.

What percentage of A2B individuals demonstrate anti-A1 in their serum?

35%.

Besides anti-A1 lectin, which other reagent can be useful in differentiating A and B subgroups?

Anti-A,B

Which reagent is also useful in differentiating various A and B subgroups because of H antigen strength?

Anti-H

The presence of weak A or weak B antigens is confirmed by what two procedures?

Adsorption, elution

In confirming weak ABO antigens, antibodies are first incubated with what kind of red cells during adsorption?

Known cells

After adsorption, what procedure is used to remove the bound antibody from red cells?

Elution

Studies of soluble A, B, or H antigens in what body fluid may help confirm ABO type?

Saliva