ABO & Rhesus Grouping
- Forward - Blood cell + anti-A, anti-B, anti-AB, anti-D
- To test the presence of antigen
- Reverse - Serum + ABO red blood reagent, (Blood cell + anti-D )
- To test the presence of antibodies
2 Methods:
Tile method (30% suspension)
- Place 1 drop of EDTA blood + 1 drop of the reagent at the particular square on the tile.
- Fully mix the solution using a toothpick and agitate for reaction.
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| O Blood sure no agglutination because there is no "Anti-O" |
 |
| Add 1 drop of reagent and 1 drop of blood. |
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| Result ( the photo shown is "AB" positive) |
Tube method (5% suspension)
- Washing *3 times* : (Reverse ✗ need)
- Fill up the test tube with 1 drop of blood and top up with normal saline
- Centrifuge at 3000 rpm for 1 minute
- Dispose the supernatant.
- Resuspend the pellet in 19 drops of normal saline (5%) (Reverse ✗ need)
- Prepare and label 4 clean tubes with Anti-A, Anti-B, Anti-AB and Anti-D. (Reverse use ABO reagents)
- Withdraw 50μl of the sample solution and release them in each of the 4 tubes.
- Centrifuge the 4 tubes in 3000 rpm for 15 seconds.
- Gently swirl the 4 tubes under light for result observation.
Result Interpretation:
- Positive result: Agglutination of RBC
- Negative result: The button dissolved followed by no agglutination. *even under microscope.*
- The Forward and Reverse test should have inverted/opposite result.
Except : Baby (Baby might not yet produce antibodies therefore the reverse result will be negative)
Du test and anti-CDE are performed when agglutination is not shown in Anti-D test.
3%~5% of antigen is the maximum amount which will form reaction with the particular amount of antibodies. Thus, 5% of suspension is used in the test.
Reference:
http://www.edu.pe.ca/threeoaks/teacherpages/higginbotham/Biology%20521%20Webpage/resources.htm
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