Blood Typing

By: Caraan, Cu, del Rosario, Dino, Dumangon, Otchengco

What is ABO Blood Group System?

Classification of human blood based on the inherited properties of the red blood cells.

Determined by the presence of Antigens A and B.

Most common blood group system.

Has four blood groups :

A, B, O, and AB blood groups.

A blood type can either be Rh+ or Rh-

The people behind the ABO Blood Group System…

Karl Landsteiner

Austrian Scientist

Discovered three of the four blood group system in the year 1900.

A, B, and O blood groups

Alfred von Decastello & Adrian Sturli

Discovered the AB blood group in the year 1900

Ludwik Hirszfield, E. von Dungern& Felix Burnstein

Discovered the heritability of ABO Blood Groups in 1924.

Correct blood group inheritance pattern of multiple alleles at one locus.

Watkins & Morgan

English scientists

They discovered that the ABO epitopes were conferred by sugars.

N-acetylgalactosamine for Type A blood

Galactose for Type B blood

ABO Blood Group System

Essential for blood transfusion

Type AB blood does not contain antibodies making it the universal recipient.

Type O blood contains no antigens makingit the universal donor.

Rh Factor

Presence or absence of the D antigen.

Defined as Rh+ or Rh-.

Incompatibility can cause Blue-Baby Syndrome of the new born.

Methods of Blood Typing

Three Manual Methods

Glass slide or white porcelain tile

Glass test tube

Microwell plate or microplate

Newer Techniques

Column technique (sephadex gel)

Solid phase tests

Slide or Tile Testing

This technique is used for emergency ABO grouping tests

It should always be supplemented with a cell and serum grouping using any one of the other above mentioned techniques.

Slide of Tile Testing

Slide or tile testing is not recommended for routine use because it is not reliable for

weakly reactive antigens on cells serum grouping with low titre anti-A or anti-B

Procedure

Place 1 drop of anti-A and 1 drop of anti-B reagent separately on a labeled slide or tile.

Add 1 drop of 20% test red cell suspension to each drop of the typing antiserum

Mix the cells and reagent using a clean stick. Spread each mixture evenly on the slide over an area of 10-15 mm diameter.

Procedure

Tilt the slide and leave the test for 2 minutes at room temperature (22°-24°C). Then rock again and look for agglutination.

Record the results.

Disadvantages of Slide Method

Less sensitive than the tube test

Drying up of the reaction mixture can cause aggregation of cells, giving false positive results.

Weaker reactions are difficult to interpret.

Tube Testing

Test tubes either of glass or plastic may be used, of lOx75mm size. The tube technique is more sensitive than slide technique for ABO grouping.

Cell grouping / forward grouping Serum grouping / reverse grouping

Cell and Serum Grouping

Spin test sample to separate serum.

Set up 6 tubes correctly labeled with donor/patient no. Anti A, Anti-B, Anti-AB, Ac, Bc and Cc.

Prepare once washed 2-5% suspension of the test cells.

Cell and Serum Grouping

Add I drop of anti-A in tube labeled A, anti-B in tube labeled B, and anti-AB in tube labeled AB.

Add 1 drop of 2-5% test cell suspension in the three tubes A,B and AB.

Cell and Serum Grouping

Add 2 drops each of the test serum in tubes labeled Ac,Bc and Cc.

Add I drop each of reagents A cells in labeled tube Ac, B cells in labeled tube Bc and 0 cells in tube labeled Oc.

Mix all the 6 tubes and centrifuge at 1000 rpm for 1 minute.

Cell and Serum Grouping

Resuspend cell button by gently shaking the tubes and read against well-lit background.

Record results according to grades of agglutination.

Direct and Indirect…

Direct ABO Blood Typing

This test detects the presence of A and B antigens on RBCs surface by means of agglutination utilizing commercial antisera.

It is a basic and simple test, it can be performed on few drops of venous or capillary blood (i.e. obtained by finger pricks) .

Indirect “Serum” Blood Typing

This test is used to confirm and must not substitute the front grouping that remains the pillar of ABO typing.

Indirect “Serum” Blood Typing

Reverse grouping is useful in resolving the infrequent but possible dubious or weak results in the front typing, and it helps to identify the rare cases of false negative and false positive results.

Antigens and Antibodies…

Inheritance of ABO Blood Types…

Inheritance of ABO Blood Groups

Controlled by the long arm of chromosome no. 9

Composed of three alleles: IA, IB, and i.

IA represents Type A blood; IB for Type B blood , and i for the Type O blood.

Type A and Type B are codominant.

Type O is the recessive allele.