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Antibody Screen Tube method


Aldorian
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Hello, to all Blood Bankers here. 
i have a question regarding about our new protocol regarding Antibody Screening.

my question is our supervisor made a new SOP about Antibody Screen and Crossmatch. In our new policy she removed the immediate spin and 37 degrees reading using Tube method . The enhancement medium we are using is ML2B LISS by BIORAD.
kindly enlighten me ? Is this possible? 
 Thank you in advance

 

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  • 3 months later...

Also, why do all of the methods I can find still include the 37C reading?  AABB Tech Manual, John Judd's book, Harmening, Blaney & Howard all reflect this (some may be older editions).  Even Immucor's instructions for their screen cells include it.  Quotient/Alba screen cell instructions list it as optional.  

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3 hours ago, Mabel Adams said:

Also, why do all of the methods I can find still include the 37C reading?  AABB Tech Manual, John Judd's book, Harmening, Blaney & Howard all reflect this (some may be older editions).  Even Immucor's instructions for their screen cells include it.  Quotient/Alba screen cell instructions list it as optional.  

My understanding is that when BB primarily used serum some antibodies like anti-Jka would show at 37 but not at AHG (this may also have something to do with albumin being the primary enhancement media at that time). Now as BB use plasma and better enhancement media this is not an issue. I would however appreciate someone correcting or expanding on this.  

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I can only go by what I was taught.

The room temperature immediate spin told us nothing, apart from the fact that there may have been a "cold reacting" antibody present, which we didn't care about and didn't want to detect, because, if it did not react at 37oC, it wouldn't be clinically significant anyway.

We also performed tube testing at 37oC, using albumin as an enhancing agent, but never once did we ever detect an antibody by this method that we did not also detect by IAT, and usually, we detected it far easier by IAT, so we stopped performing that method.  As far as I know, and we kept a weather eye opened just in case, this never caused even a mild transfusion reaction.

In answer to Ensis01, I believe what was being detected with Kidd antibodies in those days was not so much the presence of weak agglutination, but the presence of haemolysis, as serum still had complement present that could be activated, but, with the use of EDTA anticoagulated plasma, this was no longer so, as the EDTA chelated Ca++, Mg++ and Mn++, all of which are required as cofactors at the C1qrs stage of the system.  There was no reason why this haemolysis should NOT have been seen in the tube IAT when serum was used, but very few people actually looked before the addition of the saline for washing the tests before the addition of the AHG, and then, of course, no agglutination may have been seen at the end of the test, unless the AHG used was broad spectrum, including an anti-C3d.

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Thanks Malcolm!

I looked closely at my screening cell package insert and was surprised that it no longer says to perform immediate spin. It says to perform a spin at 37C but if potentiators are used to follow their instructions. We actually use PEG instead of LISS and PEG is not supposed to be spun after incubation.  I have looked at those inserts for years and never REALLY saw this wording and have no idea when these instructions changed. I knew we didn't really care about RT antibodies anymore but I thought the immediate spin was required. We have so many rules in BB and we just follow them without question.

I feel like I am in an alternate universe right now. 

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I actually pulled the package insert for our panoscreen cells from Immucor, and on page 2 the insert actually says add plasma, then cells and mix. The the next line says add potentiator, the step to do the immediate spin is no longer present. I would never have noticed this if not for this blog. There is a note that if desired the immediate spin can be performed. I do believe that I will be having a discussion with my Director and Medical Director so that I can change the procedure because if it is not needed (which in my humble opinion it is not necessary) then we need to get rid of the steps.

scott

 

 

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