BLOOD GROUPING AND CROSS MATCHING

1. IMMUNOHEMATOLOGY
DR MANJULA N

2. BLOOD GROUPING

3. INTRODUCTION
• Karl Landsteiner in 1900 first described - Human Blood Group
System.
• Mode of inheritance - Mendelian dominant fashion.
• Two important blood group systems are:-
1. ABO system.
2. Rh systems.

4. INDICATIONS OF ABO GROUPING
• Confirmation of cell grouping in newborns.
• To resolve the ABO group discrepancies.
• To avoid the Transfusion reactions.

5. ABO Antigens
• According to the ABO blood group system, there are four different kinds
of blood groups: A, B, AB or O.
• The antigen on red cells may be A/B/AB or no antigen at all.
• There are two subgroups in group A, namely A1 and A2.
• Each individual inherits two ABO genes, one from each parent and these
genes determine the ABO antigens on their red blood cells.
• Absence of both antigens, A and B on the red cells is seen in blood group
O.

6. ABO Antigen on the surface of RBC

7. ABO antibodies
• The serum of individuals who lack the corresponding red cell
antigen contains naturally occurring antibodies.
• These antibodies are against red cell A (anti-A)/B (anti-B)/AB (anti-
AB) antigens.
• These are of IgM type and do not cross the placental barrier.
• Group A has two subgroups namely A1 and A2, and similarly AB has
two subgroups namely A1B and A2B.

8. • Identification of four blood groups is based on presence or absence
of A and/or B antigens on red cells.
• According to Landsteiner’s law, anti-A or anti-B antibodies are
always present in plasma of individuals who lack corresponding
antigen(s) on their red cells.
• ABO is the only blood group system, in which if an antigen is absent
in an individual, corresponding antibody is always present in plasma.
• O blood group is the most common.
• AB group is the least common in a population.

10. CONCEPTS OF UNIVERSAL DONOR AND
RECIPIENT
• Red cells of group O donors are devoid of A and B antigens and
cannot be agglutinated by anti-A and anti-B antibodies.
• Therefore, group O persons are traditionally considered as
UNIVERSAL DONORS.
• Group AB persons are considered as UNIVERSAL RECIPIENTS.

11. OTHER BLOOD GROUP SYSTEMS
1. LEWIS
2. KELL
3. DUFFY
4. KIDD

12. ABO System and Disease
• Group O individuals 
Increased risk of developing peptic ulcer.
• Group A individuals 
Increased risk of developing gastric
carcinoma.

13. TYPES OF GROUPING
• Forward grouping / Cell grouping:- Red cells are tested for
presence of A or B antigens by employing known specific anti-A
and anti-B sera.
• Reverse grouping / Serum grouping:- Serum is tested for presence
of anti-A or anti-B antibodies by employing known group A and
group B reagent red cells.
• Both cell and serum grouping should be done since each test acts
as a check on the other.

14. • For Rh-D grouping, D antigens are tested.
• Interpreted as POSITIVE or NEGATIVE.
• Reverse grouping is not done because most Rh-D negative persons
do not have anti-D antibodies.

15. METHODS OF BLOOD GROUPING
1. Slide test
2. Tube test
3. Microplate method
4. Gel card test

16. Slide Test
• Principle : Red cells from specimen are reacted with reagent
antisera. Agglutination of red cells indicate presence of
corresponding antigen on red cells.
• Specimen : Capillary blood from finger prick / Venous blood
collected in EDTA anticoagulant.
• Reagents : ABO antisera

17. ABO ANTISERA
TYPES:-
1. Anti- A – Blue colored.
2. Anti- B – Yellow colored
3. Anti- D – Colorless
• Sodium azide is added to prevent growth of bacteria.
• Stored at 4 to 6 degree Celsius to preserve their potency.
• Antisera may be polyclonal or monoclonal.
• Monoclonal antisera are specific and are commonly used.

19. Method
• A clean glass slide is taken and divided into 3 sections using glass
marker pencil.
• Sections are labelled as anti-A, anti- B and anti- D respectively.
• Place one drop of reagent antiserum in corresponding sections.
• Add one drop of blood to each antiserum.
• Mix the antiserum and blood with separate corner of glass slide
over an area of 1 inch in diameter.
• By tilting the slide backwards and forwards, agglutination can be
examined after 2 minutes.

21. Result
• Positive : Little clumps of red cells seen floating in clear liquid
• Negative : Red cells floating homogenously in uniformed
suspension.

22. • Slide test is quick and needs only simple equipment. Hence
employed in blood donation camp and in case of emergencies.
• But not routinely used in blood banks because:-
1. Weakly reactive antigens on forward grouping and low titre anti-
A and anti-B on reverse grouping can be missed.
2. Drying of reaction mixture at edges causes aggregation , which is
confused as agglutination.
• Results of slide test should always be confirmed by cell and serum
grouping by tube method.

23. CROSS MATCHING

24. INTRODUCTION
• Mixing of recipient and donor blood samples to detect ABO incompatability
and clinically significant antibodies.
• Always done before blood transfusion.
• 2 types : Major and Minor.
• Major – testing patient serum against donor red cells. Used commonly.
• Minor – testing donor serum with patient red cells.

25. PURPOSE OF CROSS MATCHING
• Double checking of ABO errors resulting from patient misidentification of
donor unit.
• To detect the clinically significant antibodies against the red cells.
• For transfusion of platelets, FFP and cryoprecipitate cross matching is
not required.
• But for apheresis platelets containing more than 2mL red cells, ABO
compatability and cross matching is required.

26. IMMEDIATE SPIN CROSS MATCH / SALINE CM
• Purpose : to detect ABO incompatibility.
• Done for recipients without any clinically significant antibodies .
• Equal volumes of 2% saline suspension of red cells of donor and patient
serum are mixed, incubated at room temperature for 5 minutes and
centrifuged.
• Agglutination or haemolysis indicates incompatibility.

28. CROSS MATCHING IN INFANTS
• Infants younger than 4 months are not able to produce their own
antibodies.
• So, only the forward grouping is done.
• ABO and Rh grouping are done in cord blood of maternal origin.
• Initial antibody screening is done. If positive, cross matching is
required.

29. Time for test

30. Time for test
A POSITIVE
A NEGATIVE

37. THANK YOU…