Prewarm validation

[aquinlan]

Please could users of the Gel methodology for antibody screening/AHG crossmatching share any references obtained for the validation of this procedure as compared with tube prewarm methods. We have been using gel methods routinely for years but do not have in-house validation data available for assessors. We are a pediatric facility and encounter frequent cold agglutinins. I understand that prewarm techniques are controversial. If the consensus is not to use prewarm, is the alternative to ABID all cold agglutinins and XM antigen negative red cells?

[Lcsmrz]

I understand that Ortho has an official prewarmed procedure that you could get from them, so there's a first step.

We use prewarm technique only when we know what we're prewarming away. It works great for colder-reacting Ab's that we deem clinically insignificant and for attempting to ID another warmer-reacting Ab in the presence of a cold-reacting one.

How you use it depends alot on your patient population ...

[janet]

We've been using the gel for 4 years now, cold agglutinins have a distinct appearance-almost like a dual cell (my theory is that some antibody attached to the cells while at room temp., then as the suspensions warm on incubation agglutination stops or comes off. So you get some reacting near the top of the gel 3+ appearance but a cell button at the bottom.)

We will prewarm using the Ortho method but sometimes if it is a strong cold agglutinin it only helps a bit (since there's no way to warm the MTS centrifuge during the 15 minute spin!!) To clear it up completely we go to the full prewarm tube method where we wash with warm saline, etc....never letting it cool down from 37C.

We have had a few anti-M's reacting in a line across the side of the gel (almost like the card wasn't seated right in the centrifuge!!) Other than the Anti-M's we rarely get Lewis's and I only recall two Anti-P1's in the four years.

[johna]

There have been some slings and arrows thrown at the concept of prewarming in recent years but when you're in a bind with a cold auto or allo that persists through to the AHG phase what are your other options? I've been a blood banker for many more than a few years and have never encountered a problem using the prewarm for crossmatch or screening.

[S.Hunt]

We have SOP's for the Gel prewarm technique and a tube prewarm technique and have only found the Gel system to work with weak cold agglutinins ( 1+) reactions. More often than not we need the tube method to resolve our cold auto problems. Like johna from North Carolina, we are aware of the "drawbacks" of prewarming , however have rarely encountered problems.