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Practical Blood Bank Lab 1 ABO Grouping.

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Presentation on theme: "Practical Blood Bank Lab 1 ABO Grouping."— Presentation transcript:

1 Practical Blood Bank Lab 1 ABO Grouping

2 Introduction ABO blood group antigens present on red blood cells (Natural Antigens) IgM antibodies present in the serum

3 RBC Precursor Structure
Glucose Galactose Precursor Substance (stays the same) N-acetylglucosamine Galactose

4 Formation of the H antigen
RBC Glucose H antigen Galactose H enzyme is fucosyltransferase N-acetylglucosamine Galactose Fucose

5 Formation of the A antigen
RBC Glucose Galactose N-acetylglucosamine Galactose N-acetylgalactosamine Fucose

6 Formation of the B antigen
RBC Glucose Galactose N-acetylglucosamine Galactose Galactose Fucose

7 Methods for determination of ABO group of RBCs

8 Reagents Anti-A antibodies Anti-B antibodies
Anti-AB antibodies (optional) Anti-D Group A & B RBCs Slides, or Test tubes. Wooden applicator. …..

9 Procedure Verify that patient information on the sample matches information on the worksheet. Centrifuge the sample and remove the serum to a labeled tube. Add 2-3 drops of the patient’s cells to the WC tube, and prepare a washed 3% suspension. Use Patient cell suspension in forward typing. Use patient serum for confirmation ( reverse grouping or backtyping). At the End, Discard all materials in the isolation trash containers.

10 Blood Grouping: Forward and reverse typing
ABO typing is the first thing to be done before transfusion A person must receive ABO matched blood because ABO incompatibilities are the major cause of fatal transfusion reactions To catch these incompatibilities, typing is done in two steps: Forward typing Reverse typing

11 Forward typing Front or forward type using monoclonal anti-A and anti-B (commercial) , Anti-D Patient blood is mixed with serum that contains antibodies against type A blood, and type B blood. Determination of the blood type is based on the whether or not the blood agglutinate in the presence of these sera

12 Reverse Typing Back or reverse type with A and B cells
Commercially available A and B cells are used. Patient serum added to the known cells. Used as confirmatory for the forward method.

13 Grading System for Reactions


15 Washed 3% Cell Suspension
Used in forward typing , tube methods. The ratio of serum to red cells may dramatically affect the sensitivity of agglutination tests. Consistent preparation of either 2 to 5% red cell suspension is critical to any agglutination test.

16 Principle Washing cells to be tested removes serum or plasma which may contain proteins that interfere with testing, causing non-specific agglutination or rouleaux formation. Washing also removes fibrinogen, which may cause small clots. The ratio of serum to cells markedly affects the sensitivity of agglutination tests. Preparation of a 2-5% cell suspension provides cells in an optimum concentration to detect weak antibodies. Washed 3% Cell Suspension

17 Procedure Label a 12 x 75 mm tube
Transfer 2-4 drops of blood from the sample to the labeled tube Forcibly squirt saline from the wash bottle into the tube until it is about 3/4 full Centrifuge seconds at high speed (3400 rpm) Decant supernatant and shake to resuspend completely If gross hemolysis is present, repeat steps 3 to 5 until supernatant is reasonably clear After the final wash, shake the tube to completely resuspend the cells and add saline to a final concentration of approximately 3% Washed 3% Cell Suspension

18 Notes and Precautions To prevent contamination, do not touch tubes with the tip of the saline bottle. Resuspend the cell button thoroughly between washes before adding more saline to ensure complete washing. Do not attempt to mix a tube full of saline. Do not mix cells by using your gloved finger as a stopper. To prevent cells from spraying out during centrifugation, fill tubes no more than 3/4 full. To ensure good resuspension of cells, add the saline in a forceful stream. Washed 3% Cell Suspension

19 Slide Method – Forward Typing
Principle: When red cells are mixed with various reagent antiseras (soluble antibody), agglutination will occur on the slides containing cells positive for (possessing the antigen) the corresponding antigen. No agglutination will occur when the red cells do not contain the corresponding antigen.

20 Procedure: On the section of slide labeled anti-A place one drop of antibody A. On the section of slide labeled anti-B place one drop of antibody B. On the section of slide labeled anti-AB place one drop of antibody AB. On new slide labeled anti-D place one drop of antibody D. Place one drop of cells in each antibody containing circle. Carefully mix each solution with a separate applicator stick. Tilt slowly for one minute, then observe for the agglutination.

21 Interpretation of the results:
Strong agglutination of RBCs in the presence of any ABO grouping reagent constitutes a positive result. A smooth suspension of RBCs at the end of 2 minutes is a negative result. Samples that give weak or doubtful reactions should be retested by Tube test ABO grouping

22 Tube Methods - Forward Typing
- Prepare 2-5% cell suspension - Label Test tubes - Add 2 drops of Anti sera A, B , and D

23 - Add one drop of 2-5% Patient Red Blood Cell suspension.
- Mix the contents of the tubes gently and centrifuge for seconds at approx x g - Gently resuspend the RBCs buttons and examine for agglutination If the Rh test is negative, add a second drop of anti-D and incubate 15 minutes at 37oC, then centrifuge and read again.

24 Reaction of cells tested with
Read and record agglutination reaction Interpretation Reaction of cells tested with ABO Group Cell Ag Anti-B Anti-A O No Ag - A + B AB A, B

25 Serum testing (Reverse)
Label 2 clean test tubes (A, B ) Add 2-3 drops of serum to each tube Add one drop of (A) reagent RBCs to the tube labeled A Add one drop of (B) reagent RBCs to the tube labeled B Mix the contents of the tubes gently & then centrifuge for seconds at x g Examine the tubes for evidence of hemolysis. Gently resuspend the RBCs buttons and examine them for agglutination

26 Interpretation of results
Agglutination in any tube of RBCs test or hemolysis or agglutination in serum tests constitutes positive test results A smooth suspension of RBCs after resuspension of an RBCs button is a negative result

27 Interpretation of Both (Forward and Reversed Typing)
Reaction of serum tested against Reaction of cells tested with ABO Group O cells B Cells A cells Anti-B Anti-A O - + A B AB

28 Other methods for blood grouping
Gel Cards Gel Cards containing Anti-A, Anti-B, and Anti-A,B are used to test patient or donor red blood cells for the presence or absence of the A and/or B antigens. The results of red blood cell grouping should be confirmed by reverse (serum) grouping, i.e. testing the individual’s serum with known A1 and B red blood cells. In the Gel Test™, the specific antibody (Anti-A, Anti- B, or Anti-D) is incorporated into the gel. This gel has been pre-filled into the microtubes of the plastic card. As the red blood cells pass through the gel, they come in contact with the antibody. Red blood cells with the specific antigen will agglutinate when combined with the corresponding antibody in the gel during the centrifugation step. Anti-A,B reagent agglutinates red blood cells possessing A and/or B blood group antigens. Group O red blood cells will not react with the reagent. In addition, Anti-A,B is particularly useful in detecting some weak subgroups of A and B which may not agglutinate with Anti-A or Anti-B reagents.

29 Interpretation of Results
A positive reaction is recorded when red cells are retained in or above the gel column after centrifugation A negative reaction is recorded when a distinct button of cells sediment to the bottom of the column after centrifugation. A positive reaction in the MTS Control microtube indicates a false positive reaction may have occurred in the corresponding blood grouping microtube, thus invalidating the blood grouping tests. Drying, discoloration, bubbles, crystals, other artifacts, opened or damaged seals may indicate product alteration A buffered gel suspension is contained in two (2) microtubes of the A/B/D Monoclonal and Reverse Grouping Card™. Sodium Azide (0.1% final concentration) is added as a preservative. Micro Typing Systems, Inc.


31 Procedure: Suspend 50 µL WB or 25 µL RBCs in 0.5 ml diluent.
ABO/D + Reverse group cards Procedure: Suspend 50 µL WB or 25 µL RBCs in 0.5 ml diluent. Identify the card with patient's name. To microtubes l, 2, 3 & 4 add l0 µL of suspension. To microtube 5 add 50 µL Al cells + 50 µL plasma. To microtube 6 add 50 µL B cells + 50 µL plasma. Centrifuge for l0 minutes and read.

32 Microplate Technique Microplate techniques can be used to test for antigens on red cells and for antibodies in serum. A microplate can be considered as a matrix of 96 “short” test tubes; the principles that apply to hemagglutination in tube tests also apply to tests in microplate. Add reagent and patient sample( red cells/ serum) Incubation, Centrifugation Red cell resuspension,   Reading of results   Interpretation of results Shape of microplate (U, V, and strait bottom) - the U bottom is used for blood grouping.

33 Thank You

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