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srichar3

Blood Group Discrepancy

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We have a case at the moment, a patient with no history, blood group by Ortho Cassette method is Anti-A 2+, Anti-B 4+, Anti-D 4+, CTRL Neg, A1 Cells 3+, B Cells Neg.

Tube group gives B Pos and the Anti-A is totally clear Microscopically not even any apparent rouleaux, however when repeated at 4°C some small agglutinates were visible.  Washing the cells yielded no change in the Anti-A reaction and auto control is negative in poly cassette as is the Antibody Screen.  Back group tested with A2 cells also Positive. 

Is there any further tests that should be considered to try to ascertain the correct blood group? If not how would you report the blood group?

Is this likely an A Subgroup B? If so would genetics be the only way to confirm this? 

Thanks

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But going off the AABB technical manual it seems the back A cell reaction is too strong for a subgroup, and if a subgroup other than A2 it should be 1+?

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Looks like an AsubgroupB to me, but, these days, with monoclonal antibodies, which type of A subgroup can only be accurately sorted by molecular techniques.

The reverse group needs more investigation.  It could be anti-A1, it could be another "cold" antibody specificity (such as anti-M or anti-P1), or it could be a combination of the two.  If there is no reaction at 30oC and above, it doesn't really matter, but, to be on the safe side, if blood is required, I would give group B packed red cells, or group B red cells resuspended in AB plasma.

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Does look like a AsubB w anti-A1.

I'd test pt cells w A1 lectin.  Also run a small IS/rt panel of screening cells, A1, A2, auto cells and see what it looks like.  By running the screening cells along with A1/A2 cells I can get an idea if it is a cold specificity or anti-A1.

 

 

 

a

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srichar3, do let us know results of other tests and if the patient was treated as AsubB for transfusion. I’m curious as to why the patient would have such a strong reaction with A reverse cells if they are a subgroup (I have only seen 1+ in reverse with A cells in subtypes but of course YMMV) and wonder if perhaps there is some pertinent clinical information causing false positive results with anti-A in gel, such as pH- or reagent- dependent reactivity. Especially since it was just BPos in tube method.

Edited by Oniononorion

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I tested the back group against 4 of each ABO group, Reacted 3+ with all A and AB samples and Negative with group O and B so its defiantly an Anti-A and not another cold antibody interfering.

Also did A1 lectin and that was neg.. 

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56 minutes ago, srichar3 said:

I tested the back group against 4 of each ABO group, Reacted 3+ with all A and AB samples and Negative with group O and B so its defiantly an Anti-A and not another cold antibody interfering.

Also did A1 lectin and that was neg.. 

Did you really mean "an Anti-A", and not an Anti-A1?  Surely, if the A antigen is expressed on the red cells, however weakly, the patient cannot produce an anti-A, unless it is an auto-antibody?

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2 hours ago, Malcolm Needs said:

Did you really mean "an Anti-A", and not an Anti-A1?  Surely, if the A antigen is expressed on the red cells, however weakly, the patient cannot produce an anti-A, unless it is an auto-antibody?

I meant it in the sense that it's an antibody reacting with the A antigen rather than another cold reacting antibody reacting with another antigen on the Acells been the cause. 

However as per my original post it did react with A2 cells this along with the strength of the back group was why I was questioning and AsubB.

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2 hours ago, Malcolm Needs said:

Did you really mean "an Anti-A", and not an Anti-A1?  Surely, if the A antigen is expressed on the red cells, however weakly, the patient cannot produce an anti-A, unless it is an auto-antibody?

In your experience does the fact the Anti-A is reacting with A2 cells rule out A subgroup of A been present?

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2 minutes ago, David Saikin said:

Did you test your A2 cells in gel or in tube?  If in tube, did you look at it microscopically?

I would have to check with the tech who performed it.

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3 hours ago, srichar3 said:

In your experience does the fact the Anti-A is reacting with A2 cells rule out A subgroup of A been present?

Certainly when the A antigen on the red cell is sufficiently strong to give the reaction you posted earlier.

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10 hours ago, David Saikin said:

Did you test your A2 cells in gel or in tube?  If in tube, did you look at it microscopically?

The A2 was done in Gel, or rather glass beads as Ortho is out here. The left well is A2 and the right is A1 so clearly weaker reaction with A2 but still reacted. I also repeated the tube method and when I did it, A1 gave strong reaction and the A2 was barely visible by eye by but large agglutinates observed microscopically. 

Any suggestions for further tests I can do on this one? or would genetic testing be the only way to resolve this now?

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Found an old Bio-Rad card that is still in date so decided to give it a try in that and its shows a plane old B Pos! But the Ortho gives a consistent 1 or 2 + A reaction in 3 different cassette types. 

Awaiting an explanation from Ortho. 

ScreenHunter_003.jpg

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I guess there are two possibilities:

1.This patient is AsubB, the A antigen cannot be tested by some anti-A reagent.

2.This patient maybe has some antigen rather than A which is crossreacted with the component of the reacted reagent.

solution are

1.How about test the patients' red cells against some B type human serum, please make sure that there are O cells as negtive control. The monoclonal reagents are not as complete as the human source polyclonal antibodies.

2.And to test the saliva for ABH substance in it( if the patient is a secretor).  And do genotyping, just so expensive.

 

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Could it be a B(A) phenomenon with elevated level of B transferase and decreased activity of the anti-A (and anti-A1)? 

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I am not sure about the difference between B(A) and AsubB, I always thought we define B(A) based on genotype not phenotype, and the AsubB maybe the genetic product of B(A).:blink:

Edited by yan xia
typo

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The reaction with the A2 cell would show there is an anti-A (+an anti-A1) so I presume it would rather speak for a B(A). I would expect for a AweakB having an anti-A1 only (?).

 

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1 hour ago, Arno said:

The reaction with the A2 cell would show there is an anti-A (+an anti-A1) so I presume it would rather speak for a B(A). I would expect for a AweakB having an anti-A1 only (?).

 

Or, it could be that, as there is a sort of continuum of antigen strength between A1, right down to Ael, and Dolichos biflorus reacts with the A antigen, as well as the A1 antigen (it is far from specific, reacting also with the Tn and Cad antigens), that the A2 red cells may not truly be an A2.

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