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Reverse Typing

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I just took over Blood Bank about 10 months ago,  but I've worked nights for over 10 years, so it's been a long time since I've done Blood Bank.   I have a 57yr old cancer patient who's typed B positive forwarding and reverse as AB.  But we put it in the refrigerator for 15 mins and it came out a 2+ in the reverse.   Never have had one like this before.  What could cause? 

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Is your patient male or female - not that it matters that much,  to be honest???!!!!!!!

IgM antibodies, which include ABO and H isoagglutinins, react optimally at 4oC, and so, if you are storing the patient's sample for 15 minutes in a refrigerator, you will be bringing down the temperature of the plasma in the sample, perhaps not to 4oC, but certainly closer to 4oC.  In addition, IgG ABO and H isoagglutinins also react at 4oC, with no need for any potentiators, such as enzyme-treatment of the red cells, and cause direct agglutination (just see an EDTA sample of a cord blood from a baby suffering from even mild HDFN due to ABO, that has been left in a fridge over night.  The baby cannot have made an IgM auto-antibody at this stage, the maternal IgM antibodies cannot have passed through the placenta, and so the agglutination seen in the sample must be down to the maternal IgG ABO and H isoantibodies).

 

So, to cut a long story short, The patient's condition can account for the reverse group at initial testing, but the temperature can certainly account for the "appearance" of the reaction after time in the fridge.

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Have seen this many times with cancer patients.   They are probably immunosuppressed and not making a lot of antibodies including isoagglutinins.   I would try room temp incubation first.   Make sure you run an autocontrol.

Edited by R1R2

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does the patient have a history of allogeneic stem cell transplant? what type of cancer does the patient have?

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JustinC, the patient has Malignant Neoplasm (colon Cancer).  Don't know about the stem cells..   Thanks R1R2....

Edited by dot

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I only found out today that you can enhance reverse group reaction by enzyme treated cell but when you perform reverse group with enzyme treated cell wouldn't it pick up other antibody?  

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1 hour ago, gagpinks said:

but when you perform reverse group with enzyme treated cell wouldn't it pick up other antibody?  

Yes, of course, which is why you MUST use enzyme-treated group O red cells (screening cells - not just one example of group O red cells) as a negative control.  If you do, and the group O red cells give a reaction, you still don't know the ABO group, until you have sorted out the specificity, and then used reverse grouping cells - and group O - cells negative for the cognate antigen.  If you don't use a negative control - you should be sacked!!!!!!!!!!

 

Nothing personal!

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