Blood typing/grouping
Apparatus and reagents
- Antisera A, B, and D
 - Lancet
 - Clean grease-free glass slides
 - Microscope
 - Slide warmer
 - Dropper
 - Normal saline
 - Toothpick
 - Cotton swab
 - Alcohol
 
Principle
The red cells contain different types of agglutinogens (antigens) and the plasma contains agglutinins (antibodies). In order to determine the blood group of a subject, the red cells are allowed to react with sera containing known agglutinins.Reaction
Agglutination results due to the reaction of agglutinogens with complementary antibodies or agglutinins.Agglutinogens + Agglutinins => Agglutination
A + Antibodies A => Agglutination
B + Antibodies B => Agglutination
Universal donor
A person with type O type i.e., B agglutinin but no agglutinogensUniversal recipients
A person with type AB i.e., A and B agglutinogens but no agglutinin.Procedure
- Obtain a clean microscope slide and divide the glass slide into three equal parts with a glass marking pencil.
 - Mark one end A, the other end B, and in the center D.
 - Pre-warm the slide by placing it on a slide warming box.
 - Lance the fingertip to obtain a good-sized blood drop.
 - Place one drop of blood on each end of the marked slide and two drops in the center of the slide.
 - Add 1 drop of anti-A serum to the A-side.
 - Add 1 drop of anti-B serum to the B side.
 - Add 1 drop of anti-d serum to the center of the slide marked as D.
 - Mix the antiserum and blood with a toothpick.
 - Spread each mixture over the slide slightly.
 - Observe the slide for any agglutination of red cells by holding the slide from one end and tilting/rotating it in all directions by avoiding the mixing of the two sera.
 - Inspect the sera first with the naked eye to see whether any clumping and agglutination have taken place or not. Confirm under the microscope.
 

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