Blood Transfusion Dependency

Question 1

What is the 3-Cell screen?

Answer 1

All red cells are O as we don’t want any A or B interaction.

Antibody screening is similar to the reverse testing for ABO. Patient’s plasma is tested against a ‘panel’ of commercial test red cells that express other blood antigens than ABO and Rh, eg Kell, Duffy, Kidd, etc, the phenotype of each is known.

Three cell screen:
- to a patient serum sample the following are added separately
- test red cells (O group) - with Kidd Jka antigen
- test red cells (O group) - with Duffy Fya antigen
- test red cells (O group) - with Kell antigen
No agglutination means there is no antibody to that antigen present

MOST OFTEN NEGATIVE TO ALL THREE.

IF THERE IS A POSITIVE WE KNOW THERES AN ANTIBODY BUT WE DONT KNOW WHAT IT IS - DO A FULL ANTIBODY PANEL

Question 2

Why is it necessary to do an antibody panel?

Answer 2

• If a three cell screen comes back positive we know that
  antibodies to that antigen are present in the patient serum, but
  we don’t know what it is.
• To determine whether a patient is likely to become transfusion
  dependent in the future
• To look for any clinically significant antibodies in patient plasma
  that may react to donor cells

Results are marked by automation, either 0 = negative + = positive
By process of elimination it is possible to work out which antibody caused the previous binding in a 3 cell screen - cant be any of those with negative antibody reactions in the panel. The final 3 columns must be filled in, graded +3 for a strong reaction and +1 for a weak reaction.
Antibodies are tested for using immediate spin (cold reacting) and AHG (warm reacting) as well as controls.

In transfusion dependent patients, it can be multiple!