Merry Xmas friends. 

My blood bank uses PEG for tube method X-matches. We use EDTA when collecting samples. So when I see that we need to put a result (Hemolysis/No Hemolysis) under the 37C incubation - I get confused. Doesn't EDTA chelate Ca from complement and therefore inactivated it. And thus will never see Hemolysis at 37C if using EDTA tubes? Thanks friends. 

Edited December 26, 20195 yr by MyHerpesItch

And to you too MyHerpesItch.

Well, yes and no!

EDTA certainly does chelate Ca++, but it also chelates Mn++ and Mg++, and all three are required as co-factors for the Classical Complement Pathway, rather than actually being part of complement, which is why you don't see immune-mediated haemolysis.

The Immucor package insert for PeG says that tubes 'may' be examined after the 37C incubation for hemolysis w/o centrifugation.

While the use of EDTA plasma basically eliminates the chance of detecting hemolytic antibodies (as Malcolm says above), some laboratories still use serum. It's possible some hemolysis might been seen in visual check before taking the serum-RBC-PEG reactants to IAT. One may also recognize loss of RBC volume after the washing process, if some of the cells were destroyed during the incubation phase.

Cool thanks guys.

On 12/26/2019 at 5:52 AM, AMcCord said:

The Immucor package insert for PeG says that tubes 'may' be examined after the 37C incubation for hemolysis w/o centrifugation.

The important part being "w/o contrifugation" - don't centrifuge the 37C incubation tubes.  Take them to wash without spinning them down or you risk false positives because PEG is so "sticky".  Always wash at least 4 times if using cell washers or you risk check cell failure.  PEG is a good enhancement medium and it is very sensitive, but it is "sticky".

You probably already know this - just emphasizing it for other readers.