Do you concentrate or dilute manufactured antibody screening cells for testing? If so, do you perform QC on the concentrated or diluted cells? Do you consider this an LDT since you are altering the manufacturer's product?

I would very much advise you to do a QC.  Depending on how you dilute them and what you dilute them with, you may not get the results you expect! (Less relevant for tube testing though)

The only time we would dilute antibody screening or panel cells would be to use the cell as a rule out cell for antibody ID.  On in date cells we would not do QC, as it is not required for antibody identification per CAP.

I would agree with those who already pointed out that if you modify a reagent of any kind (unless it is part of the prep according to the manufacturer) you would have to, at the least, document QC as you are indeed on your way to using a LDT. 

 

But anyway, why are you diluting screening cells?

Scott

The only time I have seen reagent cells diluted is when they are being used for an antibody titer, and here QC is run. The other manipulation to reagent cells that I have witnessed, but not practiced, is the replacement of the manufacturer's reagent cell solvent with blood bank saline, when trying to get rid of week non-specific reactions. I do not know if QC is run in this case. I do have to ask a dumb question though; what does LDT stand for? Keeping track of the meaning of lettered abbreviations is difficult especially when they are not used regularly enough.

Thank you in advance for any reply,

Ronald 

I assumed that by LDT, Lab Developed Test is intended -- but I may be mistaken (speaking from experience!).  LDTs have their own series of regulatory hoops to jump through in order to be used for patient testing.

Scott

Thank you Scott. So the original post makes more sense. It would seem that a manipulation of the screening cell would be considered an LDT especially in the absence of any manufacturer's instruction and testing thereof.

I think you will all find that the manufacturers do indeed have something to say on the topic.  Most IFUs (box inserts /package inserts) will have a disclaimer about products not being used in the way they were intended.  So diluting cells from 5% to 1% would definitely come under 'off-label' use unless the manufacturer specifically says you can do this and specifies what you should use as a diluent