Du Testing

 Several weak antigen D forms are recognized, including what was formerly called antigen Du. The term weak antigen D is used to describe those forms of antigen D where the number of red cell D receptors is reduced. Such weak D cells react less strongly than red cells with normal numbers of D receptors. Monoclonal IgM anti-D serum will detect weak antigen D. In some African and other populations, weak antigen D has been found in up to 10% of people.

Requirements

  •        Purple top vacutainer blood whole blood
  •        Anti-D antisera
  •        Coombs reagent
  •        Test tubes
  •        Centrifuge
  •        Microscope
  •        Slides

Procedure

  1. Prepare 5% cell suspension of patient.
  2. Place one drop of anti-D serum in a test tube.
  3. Add  to  it  one  drop  of  patient’s  cell  suspension.
  4. Incubate the test tube at 37°C for 30-60 min.
  5. After centrifugation 3400 RPM for 10 seconds resuspend the RBCs pallet, and check for agglutination, if positive report Anti-D positive.
  6. If negative, Wash the cells five times with saline.
  7. Add 2 drops of antiglobulin (Coomb's) serum mix and centrifuge at 3400 RPM for 10 seconds.
  8. Read for agglutination.  Agglutination in the test indicates Du variant.

Quality control: 

Anti-D serum should be tested against known Rh-positive and Rh-negative red cells with each batch of tests. 

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