Hello, fellow blood bankers.

I recently got a DAT positive result; poly 4+ IgG 4+ IgA 2+ IgM1+ C3c 1+ C3d 2+ control 1+ using Bio-rad DAT card.

Antibody identification revealed pan-reactivity at the IAT.

I thought this result might be caused by spontaneous agglutination of heavily IgG-coated patient's red cells.

According to AABB technical manual 18th ed, removing autoantibody by warm saline wash (method 2-17) is recommended for ABO, RhD cell typing.

I guess warm saline washing is done to remove cold agglutinins, not IgG antibody.

Is there an appropriate method to have a valid DAT result in this case? 

Please help me. Forgive my ignorance.

Maybe choloroquine phosphate can help to remove the IgG antibodies on the cells surface. And heat elution (45 degree C 15 min or 56 degree C 10 min) can do some help to remove IgG antibodies, but not as effective as to IgM antibodies.

Edited August 23, 20186 yr by yan xia
spelling error

In Immune Hemolytic Anemias Garratty suggests a warm saline wash to resolve the problem of a positive control for DATs. I've used that successfully for a patient with a pretty strong cold agglutinin, to report out a negative DAT IgG (after consultation with our medical director). It was unsuccessful for a couple of other patients with colds. It wouldn't resolve a problem with the control for IgG coated cells.

It looks to me as though you may have some spontaneously agglutinating IgM in the sample.  Do you have some neutral cards?  If so, put 50ul of the cell suspension on the neutral card and centrifuge directly.  That won't necessarily differentiate between an agglutinating IgG and an IgM but it would tend towards the latter if it were positive.

Also, in case it is LISS-enhanced, you could try suspending your cells in Cell Stab or Alsevers or PBS and repeating.  Just beware of cells 'training' through the gel.  And make absolutely sure that whatever you use has well come to room temperature before you use it!

Anyway, from those results, even though the control is positive, you clearly have a major component of IgG present.

 

4 hours ago, AMcCord said:

In Immune Hemolytic Anemias Garratty suggests a warm saline wash to resolve the problem of a positive control for DATs. I've used that successfully for a patient with a pretty strong cold agglutinin, to report out a negative DAT IgG (after consultation with our medical director). It was unsuccessful for a couple of other patients with colds. It wouldn't resolve a problem with the control for IgG coated cells.

years ago all we had was warm saline or ether.  We used warm saline on cord bloods with +DATs. 

4 hours ago, AMcCord said: