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.

1. Blood
Groups
DEFINITION AND TYPES
PRESENTED BY ENAS
EHDED
1/12/2019

2. Definition
 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.

3. ABO system
 The outer layer of RBCs membrane contain certain antigens which are chemically
glycoproteins and called agglutinogens.
 According to the presence of these antigens , human blood can be classified into
many groups.
 Most of these antigens are weak and are mainly of importance in genetic studies.

4. ABO Varieties
 The most common type of grouping is the ABO blood group system.
 The varieties of glycoprotein and glycolipid coating on red blood cells divides
blood in to four groups..
 A(A oligosaccharide is present)
 B(B oligosaccharid e is present )
 AB(AB oligosaccharide are present)
 O(neither A or B,only their precursor H oligosaccharide present)

5. ABO System
-This system includes 2 types of antigens A and B agglutinogens.
-According to the presence of A and B antigens there are 4 groups of human blood :
1- Group A (about 41% ) : when only type A antigen is present.
2- Group B (about 9 % ) : when only type B antigen is present.
3- Group AB (about 3 % ): when both types A and B antigens are present.
4- Group O (about 47 % ): when both types A and B antigens are absent.

6. Rh system (Rh factor)
 This is system of agglutinogens normally present in the red cells of Rhesus
monkey (hence the name Rh)
 This antigen was found in the human Red cells.
 Antigen D has the strongest antigenic effect So :
If D antigen is present → Rh +ve.
If D antigen is absent → Rh -ve.

7. Group O
 Approximately 45% of the population is group O.
 No A or B antigens present, think of as “0” antigens present.
 These individuals form potent anti-A and anti-B antibodies which
circulate in the blood plasma at all times.

8. Group A
 Approximately 40% of the population is group A.
 No B antigens present.
 These individuals form potent anti-B antibodies which
circulate in the blood plasma at all times.

9. Group B
 Approximately 11% of the population is group B.
 No A antigens present.
 These individuals form potent anti-A antibodies which circulate in the
blood plasma at all times.

10. Group AB
 Approximately 4% of the population is group AB.
 Both A and B antigens present.
 These individuals possess no ABO antibodies.
 NOTE: This slide is in error as it only illustrates presence of one
antigen not 2.

11. Summary

12. Determination of ABO system
 Mix one drop of blood with 1 ml of isotonic saline in a test tube.
 Put 2 separate drops of the diluted blood on a glass slide.
 Add one drop of anti-A serum (blue coloured) to one blood drop and one drop
of anti-B (yellow coloured) to the other drop.
 Mix the blood with anti-A and anti-B sera gently using the blunt end of two
separate pins.

13.  After 2 minutes examine for agglutination :
 A- If agglutination occurs with anti-A serum only , the blood group is type A.
 B- If agglutination occurs with anti-B serum only , the blood group is type B.
 C- If agglutination occurs with both anti-A and anti-B sera , the blood group is
type AB.
 D- If no agglutination occurs with either anti-A or anti-B , the blood group is type
O.

14. Determination of Rh group.
 Put 2 drops of diluted blood on a glass slide.
 Add one drop of anti-D serum to the blood and mix gently with the blunt end of a
pin.
 Examine for agglutination :
 a-If agglutination occurs , the blood group is Rh +ve.
 b-If no agglutination occurs , the blood group is Rh –ve.

16. Precautions Before Blood Transfusion.
1- Transfused blood should be compatible with that of recipient.
2- The Hb content of transfused blood must be not less than 90 %.
3- The transfused blood should be free from diseases.
4- The transfused blood must be fresh and not frozen.
5- Cross matching test should be done.

17. Complications of Incompatible Blood
Transfusion.
Incompatible blood transfusion leads to agglutinations of the donor‘s
red cells followed by their hemolysis and results in the following :
1- Severe pain elsewhere in the body.
2- Hemolytic jaundice.
3- Chest pain.
4- Dyspnea.
5- Chills and fever.
6- Hypotension.

18. Complications of Blood Transfusion
Incompatibility due to mismatched blood groups.
2- Allergic reactions.
3- Bacterial infections.
4- Transmission of diseases
5- Massive blood transfusion leads to circulatory overload.