Blood grouping

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Blood Grouping

description

AGA KHAN UNIVERSITY HOSPITAL

Transcript of Blood grouping

Page 1: Blood grouping

Blood Grouping

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History - Karl Landsteiner

Discovered the ABO Blood Group System in 1901

He and his five co-workers began mixing each others red cells and serum together and inadvertently performed the first forward and reverse ABO groupings

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Landsteiners Rule

If an antigen (Ag) is present on a patients red blood cells the corresponding antibody (Ab) will NOT be present in the patients plasma, under ‘normal conditions’.

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Major ABO Blood Group

ABO Group

Antigen Present

Antigen Missing

Antibody Present

A A B Anti-B

B B A Anti-A

O None A and B Anti-A&B

AB A and B None None

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ABO Basics

Blood group antigens are actually sugars attached to the red blood cell.

Antigens are “built” onto the red 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

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Principle of blood grouping

There are two principles

1-almost all normal healthy individuals above 3-6 months of age have “ naturally occurring Abs” to the ABO Ags that they lack

These Abs termed naturally occurring because they were thought to arise without antigenic stimulation

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Principle of blood grouping

2- These “naturally occurring” Abs are mostly IgM class. That means that, they are Abs capable of agglutinating saline/ low protein suspended red cell without enhancement and may activate complement cascade.

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ABO and H Antigen Genetics

Genes at three separate loci control the occurrence and location of ABO antigens

The presence or absence of the A, B, and H antigens is controlled by the H and ABO genes

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Location

The presence or absence of the ABH antigens on the red blood cell membrane is controlled by the H gene

The presence or absence of the ABH antigens in secretions is indirectly controlled by the Se gene

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H Antigen

The H gene codes for an enzyme that adds the sugar fucose to the terminal sugar of a precursor substance (PS)

The precursor substance (proteins and lipids) is formed on an oligosaccharide chain (the basic structure)

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RBC Precursor Structure

Glucose

Galactose

N-acetylglucosamine

Galactose

Precursor Substance (stays the

same)

RBC

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Formation of the H antigen

Glucose

Galactose

N-acetylglucosamine

Galactose

Precursor Substance (stays the

same)

RBC

H antigen

Fucose

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H antigen

The H antigen is the foundation upon which A and B antigens are built

A and B genes code for enzymes that add an immunodominant sugar to the H antigen Immunodominant sugars are present at the

terminal ends of the chains and confer the ABO antigen specificity

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A and B Antigen

The “A” gene codes for an enzyme (transferase) that adds N-acetylgalactosamine to the terminal sugar of the H antigen N-acetylgalactosaminyltransferase

The “B” gene codes for an enzyme that adds D-galactose to the terminal sugar of the H antigen D-galactosyltransferase

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Formation of the A antigen

Glucose

Galactose

N-acetylglucosamine

Galactose

RBC

FucoseN-acetylgalactosamine

A antigen

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Formation of the B antigen

Glucose

Galactose

N-acetylglucosamine

Galactose

RBC

FucoseGalactose B antigen

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H antigen

Certain blood types possess more H antigen than others:

O>A2>B>A2B>A1>A1B

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Why do Group O individuals have more H antigen than the other groups?

Group O individuals have no A or B genes to convert the H antigen to A or B antigens….that means more H antigen sites

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Group O Group A

Many H antigen sites

Fewer H antigen

sites

A

A A

AA

Most of the H antigen sites in a Group A individual have been

converted to the A antigen

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Genetics

The H antigen is found on the RBC when you have the Hh or HH genotype, but NOT from the hh genotype

The A antigen is found on the RBC when you have the Hh, HH, and A/A, A/O, or A/B genotypes

The B antigen is found on the RBC when you have the Hh, HH, and B/B, B/O, or A/B genotypes

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Bombay Phenotype (Oh)

Inheritance of hh

The h gene is an amorph and results in little or no production of L-fucosyltransferase

Originally found in Bombay

Very rare (130 worldwide)

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Bombay Phenotype (Oh)

The hh causes NO H antigen to be produced Results in RBCs with no H, A, or B antigen (patient types as O)

Bombay RBCs are NOT agglutinated with anti-A, anti-B, or anti-H (no antigens present)

Bombay serum has strong anti-A, anti-B and anti-H, agglutinating ALL ABO blood groups

What blood ABO blood group would you use to transfuse this patient??

Another BombayGroup O RBCs cannot be given because

they still have the H antigenYou have to transfuse the patient with

blood that contains NO H antigen

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ABO antibodies

Group A serum contains anti-B Group B serum contains anti-A Group AB serum contains no antibodies Group O serum contains anti-A, anti-B, and anti-A,B

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ABO antibodies

IgM is the predominant antibody in Group A and Group B individuals Anti-A Anti-B

IgG (with some IgM) is the predominant antibody in Group O individuals Anti-A,B (with some anti-A and anti-B)

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ABO antibodies

Reactions phase: Room temperature Complement can be activated with ABO antibodies (mostly IgM, some IgG)

High titer: react strongly (4+) Usually present within the first 3-6 months of life

Stable by ages 5-6 years Decline in older age Newborns may passively acquire maternal antibodies (IgG crosses placenta) Reverse grouping (with serum) should not be

performed on newborns or cord blood

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ABO routine testing

Several methods for testing the ABO group of an individual exist. The most common method is:

Serology: This is a direct detection of the ABO antigens. It is the main method used in blood transfusion centres and hospital blood banks.

This form of testing involves two components: a) Antibodies that are specific at detecting a particular ABO antigen on RBCs.       

b) Cells that are of a known ABO group that are agglutinated by the naturally occurring antibodies in the person's serum.

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ABO ROUTINE TESTING

DIRECT OR FORWARD GROUPING

Test for antigens• Patient’s cells containing unknown antigens tested with known antisera

• Antisera manufactured from human sera

Aantisera used:Antisera Color Source

Anti-A Blue Group B donor

Anti-B Yellow Group A donor

Anti-A,B Red Group O donor

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Forward Grouping

Reaction of patient red blood cells tested with Reagent anti-A and anti-B antisera

Slide: 20-40% RBC suspension + anti-serum

Tube (12x75mm): 2-5% RBC suspension + anti-serum (centrifuge before read)

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Forward Grouping

Reaction Patterns for ABO Groups

Blood group Agglutination with Anti-A

Agglutination with Anti-B

A + -

B - +

AB + +

O - -

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Reverse grouping

• serum is combined with cells having known Ag content in a 2:1 ratio

• uses commercially prepared reagents containing saline-suspended A1 and B cells

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Reverse grouping

Reaction Patterns for ABO Groups

Blood Group Agglutination with A cells

Agglutination with B cells

A - +

B + -

AB - -

O + +

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Grading of Agglutination:

Negative (0) No clumps or aggregates

Weak (+/-) Tiny clumps or aggregates barely visible macroscopically or to the

naked eye

1+ Few small aggregates visible macroscopically

2+ Medium-sized aggregates

3+ Several large aggregates

4+ One solid aggregate

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ABO blood group (forward blood grouping)

Patient Red Cells Tested With

Interpretation Anti-B Anti-A Patient

0 0 1

0 4+ 2

4+ 0 3

4+ 4+ 4

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ABO blood group (forward blood grouping)

Patient Red Cells Tested With

Interpretation Anti-B Anti-A Patient

O 0 0 1

A 0 4+ 2

B 4+ 0 3

AB 4+ 4+ 4

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Reverse Grouping (Confirmatory grouping

Patient SERUM Tested With

Interpretation

B Cells A1 CellsPatient

4+ 4+ 1

4+ 0 2

0 4+ 3

0 0 4

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Reverse Grouping (Confirmatory grouping

Patient SERUMTested With

Interpretation

B Cells A1 CellsPatient

O 4+ 4+ 1

A 4+ 0 2

B 0 4+ 3

AB 0 0 4

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Forward & reverse ABO blood grouping

Reaction of Cells Tested With

Reaction of Serum Tested Against ABO

Group

Anti-A Anti-B A1 Cells B Cells

1 0 0 + + O

2 + 0 0 + A

3 0 + + 0 B

4 + + 0 0 AB

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Forward & reverse ABO blood grouping

Reaction of Cells Tested With

Reaction of Serum Tested Against ABO

Group

Anti-A Anti-B A1 Cells B Cells

1 0 0 + +

2 + 0 0 +

3 0 + + 0

4 + + 0 0

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ID card system

This ID-Card contains a mixture of human polyclonal and monoclonal anti-A, human polyclonal anti-B and human polyclonal anti-D antibodies.

The microtube ctl is the negative control. Two microtubes with neutral gel serve for reverse grouping with A1 and B cells.

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Fully-automatic walk-away for ID-Cards

Stand alone instrument

Continuous sample loading

Continuous reagent loading

Priority samples (STAT)

Reagent stock

High throughput

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Optimized for small blood volumes

Dispense verification

Easy-to-use

Full test menu

Wi-Fi

Touchscreen 17"

Host connectivity

Internal & external validation

Capacity180 samples240 ID-Cards28 reagent vials

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Thank you….