Hi all,

We had a patient with difficult interpretation of ABO group, please have a look at the following results and help to solve the puzzle:

Anti-A: 4+, Anti-B: 4+, auto: neg, A1 cells: neg, B cells:3+;

3-cell screen: neg at all 4 phases (I.S. R.T., 37C & AHG)

According to the history so far, not a BMT recipient.

Thanks.

My worry is that this may be a case of acquired-B (although, that having been said, the reaction of the red cells with the reagent anti-B does seem to be a bit strong).

Has the patient any history of recent gut infection?

Have you tried testing the patient's red cells with different clones of reagent anti-B and/or slightly acidifying the anti-B you use as a routine reagent?

It may well be worthwhile getting this checked out by a Reference Laboratory.

Also have you tried other B cells? Could be an antibody to low frequency antigen. Not sure if reagent B cells are pooled or single donor

My worry is that this may be a case of acquired-B (although, that having been said, the reaction of the red cells with the reagent anti-B does seem to be a bit strong).

Has the patient any history of recent gut infection?

Have you tried testing the patient's red cells with different clones of reagent anti-B and/or slightly acidifying the anti-B you use as a routine reagent?

It may well be worthwhile getting this checked out by a Reference Laboratory.

We thought it looked a bit strong as a case of acquired-B, as well. How about T activation? Is it usually strong? We don't have other clones of reagent anti-B / slightly acidifying anti-B for use. We are thinking to send it to reference lab for further investigation. By the way, if it was chiasma, what would be the reverse grouping result look like in this case.

Thank you very much for your help.

We thought it looked a bit strong as a case of acquired-B, as well. How about T activation? Is it usually strong? We don't have other clones of reagent anti-B / slightly acidifying anti-B for use. We are thinking to send it to reference lab for further investigation. By the way, if it was chiasma, what would be the reverse grouping result look like in this case.

Thank you very much for your help.

Well the thing is, if you are using a monoclonal anti-A and anti-B, neither of them would react with T-activated red cells, as only polyclonal human-derived anti-A and anti-B would also contain an anti-T.

If it were a chimera, you would expect a mixed-field reaction with either the anti-A or the anti-B (or both), and with other reagent antibodies (don't know what you have in the way of other grouping reagents). Incidentally, in a TRUE chimera, the strongest reactions are not necessarily the "host" group. For example, if the "host" twin was really group A, and the "donor" twin was really group B, the donor twin could have been fully adsorbed in utero by the "host" twin, but, ex utero the host twin could group as mainly group B, and only a tiny bit group A - but the "true" group of the "host" twin is really group A.

As I understand it, and I have only seen about two or three cases of a "natural chimera" in some 39 years of working in transfusion, a chimera that is group A (for example) can have an anti-B in their plasma, but the anti-B would not react with the "other" twin's B antigen (a bit like the anti-B in an acquired-B will not react with another acquired-B that is caused by the same pathology - but may with the red cells of another acquired-B of a different pathology).

This is why I suggest the case is sent to a Reference Laboratory.

By the way, any news on any recent gut infection?

Thanks a lot for your explanation, Malcolm. Sorry for the wrong spelling of "chimera". We couldn't get any information on recent gut infection. Only thing we know is that the patient is going for a hysterectomy surgery soon. We already sent the sample to reference lab. Before sending out the sample, we were asked by them to test with anti-A1 lectin and DAT, both were negative. I guess ABO genotyping could help for this case if possible.

Can it be an BI (combination) antibody, only reactive with cells expressing B and I antigen, and maybe the I antigen of the patient is weakend. Can you test other B cells from adults and cord blood at 16oC?

cisAB? Seems to fit Issitts description (most appear A2, etc).

Good call John (although I would have expected the reactions between the reagent anti-A and the patient's red cells to be weaker, in the same way that, if it were an acquired-B, I would have expected the reactions between the reagent anti-B and the patient's red cells to be weaker).

The most confounding ABO discrepancy I ever saw could be explained only by the fact that the processing dept had separated the serum from the patient into an aliquot tube, got interrupted and came back and put some of someone else's serum in the aliquot tube too. Probably no one separated your sample in advance so this is probably not your case. Did you get a new sample? I have had some weird things that were not repeatable in a new sample.

I will use human serum from blood group A to react with this patient's cells to see the reaction(to guarantee the human sourced srum have no irregular antibodies).

Because there maybe some antibody to low incidence antigen in the reagent , just a guess. Or antibody to the reagent component in the patient's serum.

Could you please explain more about cisAB? Thanks a lot. By the way, our reference lab tested this sample and said they were sending the sample to national reference lab. As well, they said patient's cells are A1 ag. negative.

We actually received more than two samples from this patient and the results are similar.

Would a cis AB have anti-B?

Would a cis AB have anti-B?

"4. Sera from cisAB people almost always contain weak anti-B. This antibody apparently recognizes that part of the B antigen lecking from cisAB cells."

Daniels G. Human Blood Groups. 2nd edition, 2002. Blackwell Science, Chapter 2, page 42.

A wild guess. If the patient is having a hysterectomy, is it for a tumour? Perhaps the tumour is producing something that is mimicking an anti-B?

By any chance did this group AB person recently receive several group A single donor platelet transfusions somewhere. I had a patient a couple years ago that was a Group A that received 2 group O platelets before being transferred to our hospital and the Anti-A from the platelets showed up in her back type.