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The only thing I would add is that, if you really are convinced that the antibodies are HLA, and you are worried about the cross-match being positive, you could treat the red cells you are using in the cross-match with chloroquin, which will remove any HLA antigens that have been adsorbed onto the red cell surface.

So much fun and stress relieving, thanks  Merry Christmas to all. My very first post on this forum.

So much fun and stress relieving, thanks  Merry Christmas to all. My very first post on this forum.

So much fun and stress relieving, thanks  Merry Christmas to all. My very first post on this forum.

So much fun and stress relieving, thanks  Merry Christmas to all. My very first post on this forum.

So much fun and stress relieving, thanks  Merry Christmas to all. My very first post on this forum.

I composed an answer to this yesterday and must have gotten 'sideswiped' before I posted it!
 
Anyway, here's what I have to add to this conversation ...
You cannot compare gel to tube testing.  Aside from the 'sensitivity' issue (DAT could be positive in gel, negative in tube), gel has a totally different premise that needs to be taken into consideration.
Gel: Slippery RBCs will make it all the way to the bottom of the gel column during a given period of time at a given centrifugal force. Tube: Cells must be agglutinated. 1. Therefore, gel results are affected not only by coating of RBCs with antibodies, but also coating (roughening) with just about anything (proteins, medications).  In addition, changes in shape (e.g. sickling, acanthrocytosis, fragmentation) will cause a slower migration to the bottom. 
 
2. You cannot expect an auto control to give the same results as a DAT because the autocontrol has plasma in it.  (It's like all ladies are women but not all women are ladies.) Certain properties of the plasma will affect this downward migration (e.g. artifact, fibrin, TP ratio leading to rouleaux, cold agglutinins).
 
3. You cannot even expect the same 'DAT grade' with an auto vs DAT.  The autocontrol contains the same enhancement medium as the tests.  The presence of an enhancement medium will, ummm, enhance the antigen-antibody reaction.
 
Suggestion:  Don't mix your media.  If Auto Control is positive in gel, don't bother running DAT with tube method; run it using same method as the Auto Control (gel) and be sure to include a 'negative' control using a buffer card with patient's cells.
If the buffer control is positive: You cannot determine if DAT is pos or neg because the 'positive result' may be due to steric interferrence rather than 'coated with antibody'; check hemo smear for sickling, acanthrocytes, etc. If the gel DAT is positive and the control is negative, your patient cells have a positive DAT. If the gel DAT is negative, the positive auto could be a result of plasma abnormalities, check protein analysis, cold agglutin, etc. Hope I haven't overstayed my welcome ...