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Transfusing a very weak A subgroup


Mabel Adams

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We have a young (first trimester pregnant) woman who forward types as O but reverse types as A in gel and tube.  No recent transfusions. The usual steps to resolve a discrepancy (cold reverse, RT inc of forward) produced no new information except we got a 1-2+ reaction with anti-A,B in tube (but nothing with anti-A reagent in tube after 30 minute room temp incubation).  We have only one vendor's commercial anti-A.  We are going to try absorption and elution but either way we have to decide how to transfuse her to put a note in her profile.  Assuming that the eluate contains anti-A would you report her as A or as O?  If you report her as A would you add a special need in the computer to give only O RBCs?  If we report her as O we would add a comment to give her A plasma rather than O.  Whatever we do, she is going to have an unresolvable discrepant type in the computer so none of these decisions are to keep the computer happy. I want to keep her safe from getting incompatible products but still be as accurate as possible.  If we call her O they will test her baby's ABO (I know, I know) which could be wrongly typed as O (if it inherited this from mom) which makes me want to avoid testing baby, but that is not enough reason to make the decision on the mom.  I appreciate any input on the case or the transfusion decisions. 

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I would say that she is a subgroup of A, but would quite definitely transfuse her (if necessary - you may not have to) with group A blood (straightforward group A, not subtyped group A).

She will not suddenly produce an anti-A and, even if she produces an anti-A1, so what?  It is sufficiently rare for an anti-A1 to be clinically significant in terms of a transfusion reaction, that such circumstances are still reported and published (since 1911, when it was first reported that there was an A2, as well as an A1), but, in all that time, there has NEVER been a report of anti-A1 causing haemolytic disease of the foetus and newborn.  Giving her group A will not harm her in any way.  Giving her group O will possibly deprive a person who is genuinely group O, blood, which will no longer be available.

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I guess the only risks to her of giving A red cells would be if our testing is mistaken or the next time she comes in bleeding it isn't really her but someone who is O with a missing reverse antibody that we assume is her.  (Definitely chasing unicorns here.)  We should be able to convince ourselves it is her as long as the new sample reacts the same as now including with anti-A,B, right?  No one is likely to have time to repeat the absorption/elution.  I want to leave clear instructions on her record for whatever unlucky generalist has to deal with this someday. Or would we stay with O unless/until we repeated the adsorption/elution on each specimen?

 

BTW, can we debate why they changed "absorption" to "adsorption" 20ish years ago (ad is Latin for "to"; ab is Latin for "from")?  It seems like we are usually trying so absorb antibody out of a plasma sample so "ab" makes more sense to me.  Here we are trying to adsorb it onto the patient cells.  I was using "absorption" because it is opposite of usual, but I had the Latin prefixes backward in my mind.  I vote for a patient-sample-centric universe so "absorption" for the usual warm auto workup and "adsorption" for this sort of testing.  Or less highfalutin use of language altogether and just use "absorption" because it is a more common word.  I'm also interested in input from blood bankers from countries where English isn't the primary language.

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The adsorption/elution showed anti-A but not at immediate spin.  It reacted 2-3+ with 3 sources of A1 cells (2 different vendors' reverse cells plus an A1 donor) after 30 minutes at room temperature and was negative with 2 O reagent cells.  Last wash was all negative.  It doesn't matter, but what subgroup do you think it is? Am?  

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It doesn't matter Mabel.  There is a continuum from A2 to the weakest possible A type - but they are still group A (it is a moot point as to whether the really, really weak group A individuals should be given group O blood - see the Blood Group Antigen FactsBook), but who really cares what label they are given?  They are a weak sub-group of A.  I admit that it matters to people like Martin Olsson (for whom, I should say, I have enormous respect), but they are people who are looking at things at the molecular level, rather than the serological level.

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On ‎12‎/‎9‎/‎2019 at 3:25 PM, Mabel Adams said:

BTW, can we debate why they changed "absorption" to "adsorption" 20ish years ago (ad is Latin for "to"; ab is Latin for "from")?  It seems like we are usually trying so absorb antibody out of a plasma sample so "ab" makes more sense to me.  Here we are trying to adsorb it onto the patient cells.  I was using "absorption" because it is opposite of usual, but I had the Latin prefixes backward in my mind.  I vote for a patient-sample-centric universe so "absorption" for the usual warm auto workup and "adsorption" for this sort of testing.  Or less highfalutin use of language altogether and just use "absorption" because it is a more common word.  I'm also interested in input from blood bankers from countries where English isn't the primary language.

In a grammatical sense, and from one who has studied Latin, isn't the usage dictated by the indirect object of the sentence? You're adsorbing bound antibodies to phenotypically known cell lines, and therefore interpreting the product that had antibodies pulled towards it. The whole point is to take off the antibodies (direct object) in a way you could identify them to selected RBCs (indirect object). Up for debate  :coffeecup:

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On ‎12‎/‎9‎/‎2019 at 4:51 PM, Mabel Adams said:

The adsorption/elution showed anti-A but not at immediate spin.  It reacted 2-3+ with 3 sources of A1 cells (2 different vendors' reverse cells plus an A1 donor) after 30 minutes at room temperature and was negative with 2 O reagent cells.  Last wash was all negative.  It doesn't matter, but what subgroup do you think it is? Am?  

Ael? Or am I dating myself?  I agree with Malcolm, for transfusion purposes, it doesn't matter what you call it.

And ADsorption vs ABsorbtion ... I always looked at it this way: It depends on whether you are looking at the cell or the plasma.  Antibodies are Absorbed from Plasma and Adsorbed onto RBCs.

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