What would cause these results?  I don't expect the A1 lectin testing to look like the other tube testing in most weak subgroups that I know of.  I also thought maybe the reaction with anti-A,B would be stronger. We are still getting answers to whether there may have been a marrow transplant.  The leukemia question was about suppressed antigen expression.  Chimera?  What else?  Patient is a pregnant Native American. I assume first trimester because this is initial prenatal testing.

 

This is a very intersting case. As there is no transfusion history and leukemia, I prefer it is Chimera. Maybe we can test other red cell antigens such as the Rh system to prove or exclude it. 

Another tip: I remember there is a saying that the anti-A1 lectin is not so specifical against A1 antigen. Sometimes it will react weakly with A subgroups.

Edited March 27Mar 27 by Yanxia
typo

On repeat in another person's hands, the reactions I showed above as W+ were stronger and mixed field.  The positive part came off like a big chunk that was 3-4+ (a bit weaker with the lectin) and the rest was a sea of free cells.

A3 cells are characterized by mixed field reactions with anti-A and anti-A,B. I don't know what they do with anti-A1 lectin and it may vary depending upon which manufacturer's product you use. As Yanxia pointed out....crude Dolichos extract is NOT specific. Manufacturers formulate (dilute) it to differentiate between A1 and A2 expressions of antigen.

Dolichos biflorus (Horse gram) is amongst the best known lectin in the serologist’s tool kit, but beware!.

The lectin also agglutinates A, B, AB and O red cells that are Cad+ or Tn+.

In addition, as Yanxia so correctly says, it will react with some red cells that are A2 (or, indeed, other subgroups of A) unless the reagent is suitably diluted.

By he description of the agglutinates, I would also favour a possible chimera, as my own experience of A3 is that the agglutinates are usually quite small.  However, as you yourself say, it could be the result of a stem cell transplant of some kind.  I did my project for Fellowship of the Institute of Biomedical Science on blood groups of bone marrow transplant recipients when I was at Westminster Hospital (way back in the last century - well in the 1970's anyway) and found that group A recipients of group O bone marrow transplants, if they were Secretors, sometimes retained a sort of chimera that reacted with both anti-A and anti-A,B as a result of adsorbing soluble A substance onto the group O red cells (with no other apparent mixed-field reactions with other specificities), but did not appear to produce an anti-A post-transplant, or, if they did, it seemed to be adsorbed onto the (apparent) group O red cells coated in soluble group A substance, and had a weakly positive DAT.  Having said all that though, the female patients were usually sterile, and required either donated ova, or had their own eggs frozen prior to the transplant treatment.

Our repeat testing was on the CBC tube.  I once had a phlebotomist reuse a tube that had a flash of someone else's blood in it so wanted to make sure more than one tube on the patient reacted the same.

Confirmed no BM transplant, no history of leukemia, no recent transfusions, and not born a twin. She is Native American.  We are calling her A pos and assuming she is a weak subgroup or chimera.

Thanks for that Mabel Adams.

It may still be worthwhile having a karyotype performed as, in very unusual cases, a twin pregnancy can be completely absorbed into a single foetus, resulting in a single baby.

Are any other antigens showing mixed-field reactions?

We haven't tested any other antigens, although that would be interesting.  Which would give us the most information?  Her RhD looks typical.  I know some Native American tribes have a higher percentage of R2R2.  Maybe testing for E & C would be good?  Also, I can't think how this additional testing will change how we manage this patient.  Am I missing something?

I was thinking of antigens such as M, N, S, s, Fy^a, Fy^b, Jk^a and Jk^b.  However, they would only tell you if the patient is likely to be a chimera.

As far as what to give the patient, you are right in saying that these results would not help too much, if at all.

From what you have described, group A, D Positive cross-match compatible units should be fine.