ABO Blood Group Biochemistry Basis

GENERAL OBJECTIVES1. Discuss the composition and importance of RBC membrane

2. Discuss the role of genetics and sugar in determining blood type

3. Discuss and compare direct and indirect blood typing: major and minor crossmatching

4. Discuss the biochemical basis of ABO and RH incompatibility

5. Discuss the clinical management of Hemolytic disease of the newborn

Composition of the RBC Membrane Ailen M. Dumas

Objectives• Discuss the composition and importance of the RBC membrane

❑ Illustrate and describe the RBC membrane

• Discuss the role of genetics and sugars in determining the blood type

❑ Explain the role of genetics in determining the blood type, specifically in the oligosaccharide content of the red cell membrane’s glycolipid

Red Blood Cell

Red Cell Membrane

• Consists of the following:

• Proteins - 50%

• Lipids - 40%

• Carbohydrates - 10%

Importance of Red Blood Cell Membrane

✓ T o m a i n t a i n t h e characteristic shape of the red cell

✓ T o s e p a r a t e t h e contents of the cell from the plasma

✓ To regulate intracellular cation concentration

Red Blood Cell General Structure

Role of Genetics and Sugars in Blood Typing

The ABO Blood Group

• A classification of human blood based on the inherited properties of red blood cells

• 4 Phenotypes: A, B, AB, O

The ABO Gene

• Located on chromosome 9

• Codominant in expression

• 3 allelles: A, B, and O

• O gene is considered as amorph

fathermother

A B O

A AA AB AO

B BA BB BO

O OA OB OO

ALLELES BLOOD TYPE

A + A = A

A + O = A

A + B = AB

B + B = B

B + O = B

O + O = O

ABO Group

Antigen on Cell

Antibody in Serum

Genotype

O None Anti-A, B O/O

A A Anti-B A/A or A/O

B B Anti-A B/B or B/O

AB A and B None A/B

The ABO Blood Group Bioanimation

The ABO Blood GroupBioanimation

Rh+ Rh+

Rh+ ++ ++

Rh+ ++ ++

Rh- Rh-

Rh- -- --

Rh- -- --

Rh+ Rh-

Rh+ ++ ++

Rh+ +- --

Rh+ Rh-

Rh+ ++ +-

Rh+ ++ +-

Role of Oligosaccharide Chains on Blood Typing and

CrossmatchingArianne Valerie B. Escritor

Objectives• Discuss the role of genetics and sugars in determining the

blood type

❑ Explain the oligosaccharide sequence in the RBC membrane of the different blood types (A, B, AB, O and Bombay blood type)

❑ Discuss the biochemical basis of blood type determination. What are the different blood types and the immunodominant sugars present in the blood type

▪ Discuss and compare direct and indirect blood typing: major and minor-crossmatching

▪ Discuss the biochemical basis of ABO and Rh incompatibility

ABO Basics• Blood group antigens are actually

sugars attached to red blood cell

• Individuals inherit a gene which codes for specific sugar(s) to be added to the red cell

• The type of sugar added determines the blood group.

Biochemical Structure of Precursor Substance

• A, B and H antigens are built on oligosaccharide chains of 4-types

• The most common forms are Type 1 and Type 2

• Type 1: Carbon one of Gal is attached to the carbon three of GlcNAc

• Type 2: Carbon one of Gal is attached to the carbon four of GlcNAc

Biochemical Structure of H Antigen• Required to produce either A and B antigens

• This also applies to blood type O

H Antigen

• HH and Hh will produce the H antigen

• hh do not produce the H antigen and will have the Bombay phenotype

Bombay Phenotype (Oh)

• Absence of ABH antigens

Biochemical Structure of A Antigen

Biochemical Structure of B Antigen

Biochemical Structure of AB Antigen

• Contains both A and B gene, thus able to produce both A and B antigen

Biochemical Structures

Biochemical Structures

Gene Glycosyl transferases and

Immunodominant Sugars

ABO Blood Group System

• Discovered by Karl Landsteiner and his co-workers

Landsteiner Law: 1. Ag on RBC determines the blood group

2. The corresponding Ab is never found in the individual’s serum

3. The opposite antibody is always present in the individual’s serum

Blood Typing

1. Direct or Forward Typing

– detect Ag on red cells

2. Indirect or Reverse Typing

– detect Ab in serum or plasma

Direct Blood TypingPx

123

Direct Blood TypingPx

123 A B

Direct Blood TypingPx

123 A B

Direct Blood TypingPx

123 A B

Direct  Blood  Typing

Indirect Blood TypingPx

123

Indirect Blood TypingPx

123

Px 1

23

Indirect Blood TypingPx

123

Px 1

23 A B

Indirect Blood TypingPx

123

Px 1

23 A B

Indirect Blood TypingPx

123

Px 1

23 A B

Indirect Blood Typing

Indirect Blood Typing

Cross-matching

1. Major crossmatch (PS-DR)

- Patient’s serum + Donor’s red cell

2. Minor crossmatch (DS-PR)

- Donor’s serum + Patient’s red cell

Major CrossmatchingD

onor

X

Reci

pien

t Y

Major CrossmatchingD

onor

X

Reci

pien

t Y

Major CrossmatchingD

onor

X

Reci

pien

t Y

Minor CrossmatchingD

onor

X

Reci

pien

t Y

Minor CrossmatchingD

onor

X

Reci

pien

t Y

Minor CrossmatchingD

onor

X

Reci

pien

t Y

Biochemical Basis of ABO and Rh Incompatibility Arianne Valerie B. Escritor

The Rh Blood Group System

• “rhesus” monkey

• Red blood cell surface antigen

• Erythroblastis fetalis - Rh-negative mother is exposed to the Rh-positive blood cells of a fetus

The ABO Blood System

ABO-Rh Incompatibility

• A condition that occurs if two different and incompatible blood types are mixed, causing an immune response in the person, and may sometimes even lead to death.

• Central Dogma of Antibody Production

“One produces an antibody against an antigen foreign to them.”

The ABO Blood System

Clinical Management of Hemolytic Newborn Disease

Karlyn Abigaelle D. Del Rosario, RN

Objectives

• Discuss the clinical management of Hemolytic disease of the newborn

Overview• A.k.a. the hemolytic

disease of the foetus and newborn

• Autoimmune condition that develops in a fetus, when the IgG molecules produced by the mother pass through the placenta

• Among these antibodies, some attacks the RBC’s in the fetal circulation

Pathophysiology of the Disease

Signs and Symptoms• During Pregnancy

• Amniotic fluid may have yellow colouring and contain bilirubin

• Ultrasound of the foetus shows enlarged liver, spleen, or heart, and fluid buildup in the fetus’ abdomen, around the lungs, or in the scalp

Signs and Symptoms

• After Birth

• Pale color due to anemia

• Jaundice

• Enlarged spleen and liver of the newborn

• Anasarca

Diagnosis

• During Pregnancy

• Rh Testing

• Ultrasound

• Amniocentesis

• Coombs Test

Diagnosis

• After Pregnancy

• Testing of umbilical cord blood for blood group, Rh factor, RBC count, and antibodies

• Bilirubin test

Treatment• During Pregnancy

• Intrauterine blood transfusion of RBC into the baby’s circulation

• Early delivery if complications develop

• After Birth

• Blood transfusions

• IV Fluids

• Oxygen therapy

• Intravenous Immunoglobulin (IVIG)

Prevention• Rh (-) mothers are sensitised

by administering Rh immunoglobulin also known as RhoGAM

• RhoGAM is given at the 28th week of pregnancy

• After birth, the mother must receive a second dose of RhoGAM within 72 hours, if her newborn is Rh positive, otherwise, no need for another dose

Thank you! MD-1A | Group 6