WisKnow

Thank you Maicolm! Patient is 46 years old. Dx: Lumbar foraminal stenosis

There is a way of confirming it by genoty[ing, but it would cost the Earth for very little return.
I would like to know how old is the patient and what is the underlying pathology?
You have to remember that the the A, B and H antigens, in common with other carbohydrate-based red cell antigens, are not direct gene products, simply because only proteins can be direct gene products, whilst sugars cannot.  In the case of an AB individual, at least two different transferase enzymes are responsible for conferring either the N acetyl-D-galactoseamine residue, in the A antigen, or the D-galactose residue, in the case of the B antigen.  These two enzymes are in direct competition with one another as to which one "wins the race" to convert the H backbone to either A or B; sometimes the "A transferase" wins, and sometimes the "B transferase" wins.  In this case, it could be that the A-transferase is winning "hands down", and that the B-transferase is "whimping out a bit"!  Sorry, that last bit wasn't written exactly scientifically, but I hope you understand what I mean!

Mabel is quite correct - I also remember that there were a number of ticklish "administrative" issues.
A more technical note: Since the volume red cells from one cord are small, I suspect the the products that were distributed were POOLS of cord cells. That is the only way that the manufacturers could have enough volume to make a viable product.  A pool would mean a mix of phenotypes and the product wouldn't be much for the application suggested by WisKnow.

Mabel is right on with her reply

Back in the day, they used to include a vial of O cord cells with panels.  I believe they quit because they had not had a practice of getting consent to use those cord cells.  I imagine it would be quite a headache to set up a system for getting consent and the parents might expect to be reimbursed for the commercial use of their baby's cells.  If I am remembering correctly, I doubt that anyone will be producing cord screen cells any time soon in the US. 

Personally, I think that if the antibody does not react at 30oC or above, you have been wasting your time, effort and reagents.  Even if it does turn out to be anti-N, anti-N is almost always clinically insignificant, unless the patient is S-, s-, when they will also be 'N' negative, or if they are homozygous for one of the HE genes, or are double heterozygous for two of the HE genes - all of which are very rare.  Would you really give N Negative blood in the situation you describe?

I am pretty sure we do not do a 4C incubation routinely for any reason.
Scott

That's sort of what I meant Scott (although I think I could have put my own post better!).

Must agree that I favour an anti-Pr from your description.

So, I have this guy with what looks like anti-i (or iH).  I.S. rx are 1+w with all cells except 2 cord bloods are 3+.  5 min @room temp screen cells are 1+, cords are 4+.  Auto ct is negative at both phases.  After  5 min at 4C screen cells and auto are 2+, cords are still 4+. I like anit-i.  Prewarmed studies with Peg/anti-IgG are negative (one cell +/-).   I'm calling him with anti-iH and a cold auto aggl, specificity undetermined.
 
The patient is B Pos.  2 B+ rbcs are compatible at immediate spin and at ahg using anti-IgG and PeG in a prewarmed system.    Pt receives 2 u post-op.  He also receive 1 u a year ago post-op (same serologies noted then).
 
I send him to my reference lab hoping to get a nice report that I can use to QA my workup.  They get unspecified cold.  That's it.  They don't run it vs cord cells HOWEVER, they do enzyme pretreat it and the reactivity goes away.  anti-Pr?  I'll have to test that out here with my remaining plasma and cord cells too.  He also has a very weak +DAT with anti-complement on his post transfusion specimen.  I'll have to check that too.
 
Any and all suggestions and comments will be gratefully accepted.
 

Interesting, those of us doing electronic crossmatch would never see this.

It seems like we are seeing more strange antibodies these days.  We had a known B+ patient that was only compatible with group O red cells recently.  ABS was negative.  RG as an O.

If I understand it correctly, the lab tested an eluate that they had made against reagent A1 and B cells and it was negative; and the reference cetre tested the donor cells - with an eluate that they had made or with the eluate that the lab had made?  I suspect they made their own eluate....Could be down to a difference in method for the elution.  Also - from the same sample or a different sample? 

Reagent red cells certainly do not "express antigens weakly". There is no way a commercial entity would risk distributing a product that might give rise to customer complaints - the regulating bodies (the FDA in the USA) would be all over those issues. There may be some weakening of antigen strength over the life of commercial red cell products, but this weakening would probably only be noticed with a borderline, wishy-washy antibody - perhaps you have stumbled upon such a beast.
Commercial reverse cells (A1, A2, B, O) are washed extensively before preparation of the products. Additional washing will not "uncover more antigen sites". At most, washing (with saline) will remove the commercial red cell diluent/preservative and change the chemical environment of the test system. This change may indirectly enhance or suppress reactivity of some antibodies.
If you are using unwashed cells in ABO tests, remember that ABO substance will also be in the plasma/serum and may neutralize an antibody before it has a chance to bind to the red cells. In such a case, washing will definitely enhance reactivity.

Could be the antibody is directed against an element of the plastic bags that are used for the blood and blood components, but are not used for the reagent red cells.  It would not be the first time this has been reported, but then, why not the group O units of blood and blood components?

The PLT was A but the RBC was AB

For every test 'system', you must evaluate competency with all of the following elements:
Direct observation - test performance, including patient preparation, specimen handling, processing, testing, performance of instrument maintenance, function checks Review recording and reporting test results, review worksheets, QC records, PT results and preventative maintenance worksheets Written exercise to assess knowledge of policies and procedures, problem solving skills Verbal questions which are related to the task or job performance to assess knowledge of lab and Blood Bank policies, procedures and problem solving skills Survey participation - must analyze samples according to policies and procedures used for patient testing and must get the 'correct' results Practical w/ wet samples to assess test performance - can use previously analyzed samples or blind samples So, if I'm evaluating competency for the test system 'antibody detection', I would observe the tech performing an antibody screen. I can ask them to use the Echo and repeat the test manually. They would be expected to perform any necessary QC. The sample they are using could be a patient sample from normal work flow OR I could use a wet sample (blind sample)/survey sample. Using the second option covers 2 elements in one observation. In addition, while the tech is working I would ask questions about how the testing was performed, what he/she would do if a particular problem arose, instrument trouble shooting questions, what if blood is needed before the screen is finished, etc. That's 3 elements covered. Once they've finished with the sample, I can review their documentation and that would cover all or part of the 4th element, depending on what they did.
The more elements I can pack into the direct observation time, the quicker the tech is checked off. In this example, if I included questions about antibody detection - problem solving, method, etc in the written exercise, fifth element checked off. Once that person has done a survey sample, element #6 is covered.

 

But, because of this Mabel, it would surely still come under the heading of a DSTR, rather than a DHTR, as there appears to have been no clinically significant sequelae for the patient?

I suppose a slow primary immune response from the O neg units must be the reason the antibody took a month to appear?  Probably the first bits of antibody produced were adsorbed out by the transfused cells, no?  Maybe the DAT would have been positive one of the times you tested the patient since the O neg transfusion but you had no reason to run it.

Well to round off the case, I would do a DAT, but that is all.  Unless there are clinical reasons for so doing, I wouldn't perform an eluate, whatever the result of the DAT.

Under the circumstances you describe, and given the specificity of the antibodies involved, I am not surprised that the plasma does not appear either haemolytic or icteric.  It sounds like any red cell destruction would be slight and the process prolonged (a relatively few red cells being destroyed per day over several days).  I would not expect the plasma to show signs of red cell haemolysis, unless there was overwhelming red cell destruction, as Rh antibodies (except for incredibly rare examples) do not take the classical complement pathway through to the membrane attack complex, and may no initiate the pathway at all.
From your description, I would think this is much more likely to be a DSTR than a DHTR, and, were it me, I wouldn't spend ages working on it.
 

Thank you Heather.

Do you have the IRL Standards?  It seems that is where the supervisor definition will be explained.  I no longer assess (after 20+ yrs) - did transfusion svc and donors.

I'm not an assessor, so my advice would be............contact AABB and ask them directly. I've asked about several things and have gotten helpful replies in a short time.

I checked with AABB years ago for information, took the New assessor training and test at the AABB Conference that year.   If you meet the IRL Standards for Supervisor and are attending the AABB Conference in Anaheim, sign up for the New Assessor Training course on Thursday Oct. 22.
AABB Staff are usually very helpful in obtaining answers.  It is worth looking into the requirements and going from there.