Cord blood ABO result

[geohui]

I'm working in one private laboratory in Hong Kong, one of our client is a stem cell bank company. The company have cord blood samples sent to us for ABO&Rh typing.

I do not have any working experience in hospital or stem cell laboratory, so I have some questions about the cord blood samples for ABO testings:

1. Why the stem cell companies need to do the ABO&Rh typing on cord blood samples? Theoretically, the cord blood sample is not a baby's blood or mother's blood. If the companies need to know the baby's grouping, the better way is they can test on the baby's directly. Agree?

2. Most of the cord blood samples can give very clear-cut ABO results, however there is a few samples will give very questionable results, like mixed field (a small solid clump with cloudy background in tube method and displayed double cell populations in gel column). How can we report these samples and what further actions can be taken to protect ourself? We suggested the company repeat the test on baby's blood, but they refused. The reason is: it will border the client and will make the client query the cord blood sample is correct or not.

3. If the cord blood sample is Anti-D negative, it need to do weak D test or not?

Thanks for your help.

[SMW]

1. Cord blood is the baby's blood so a clean cord sample should test the same as a sample from the baby.

2. Likely, the cord sample was contaminated with maternal blood during the harvesting of the cord blood. This will then result in the mixed field reactions you are seeing since there are 2 populations of cells present in the sample (mother and baby). You should report the test results as invalid or unable to determine due to mixed population of cells.

3. To determine if the cord/baby sample is D-negative, you will need to test for weak D.

[Malcolm Needs ☆]

Another answer to query number 2 is that the ABO transferase enzymes of the baby are not working to anything like full capacity, and it may well be that you are getting a true double population of red cells, but all from the baby (some will be, for example, group A, and the others will appear to be group O, as the A antigen is not well expressed on all the baby's red cells.

All that having been said, you still have no alternative than to report it as SMW states - invalid or unable to determine due to mixed population of cells. In this case, however, a fresh sample from the baby will also give this kind of reaction, and so you will be unable to give a definitive answer.

:redface::redface:

[L106]

Malcolm -

If we get unusual testing results with a cord blood sample, we will obtain a heelstick sample from the baby. If we test the heelstick sample and observe similar results (ie: weak A antigen), why do you say we should report out "unable to determine due to mixed population of cells" rather than report the baby to be "Group A"?

Donna

[Malcolm Needs ☆]

Malcolm -

If we get unusual testing results with a cord blood sample, we will obtain a heelstick sample from the baby. If we test the heelstick sample and observe similar results (ie: weak A antigen), why do you say we should report out "unable to determine due to mixed population of cells" rather than report the baby to be "Group A"?

Donna

Well, the reason I say that is because, with recipients (as in the case of the baby with the heel *****) we can be, and often have to be, pregmatic, rather than dogmatic, about results (in other words, we have some leeway to interpret our results).

With donors, however (as in the case of stem cells derived from cor blood), we tend to have to be more dogmatic with our results, rather than pragmatic (in other words, we have less leeway to interpret our results).

Very often, if we have a donor whose ABO blood group cannot easily be interpreted, we disqualify the donor, rather than designate them as A, B or AB (never group O). The only time tat this "rule" is broken is with the D antigen, when, if there are any questionable resultswhatsoever, we err on the side of safety, and call them D Positive.

This is only my opinion, of course, and I could well be wrong.

:):)

[L106]

Oh, that makes perfect sense. I now understand that you were recommending the "unable to determine" terminology specifically for donor situations (not for newborn infants.) Thanks for clearing that up!

Donna

[rravkin@aol.com]

Another answer to query number 2 is that the ABO transferase enzymes of the baby are not working to anything like full capacity, and it may well be that you are getting a true double population of red cells, but all from the baby (some will be, for example, group A, and the others will appear to be group O, as the A antigen is not well expressed on all the baby's red cells.

All that having been said, you still have no alternative than to report it as SMW states - invalid or unable to determine due to mixed population of cells. In this case, however, a fresh sample from the baby will also give this kind of reaction, and so you will be unable to give a definitive answer.

:redface::redface:

Malcolm,

Your post here is very interesting, as most are, and it provoked so many questions. I will limit them to a few. If this enzyme is not working to full capacity does that effect the circulating life of the fetal RBC by reducing it? And if so is there potentially an overall underdevelopement of the infant and/or the fetus? And is it safe to assume that this is a genetically tramsmitted condition?

As far as the specifics of the low enzyme activity, is it caused by a deviation of normal enzyme structure or is the enzyme concentration decreased from normal, or is there a deviation of normal substrate structure or a decreased substrate concentration, or some combination there of, or some other reason entirely. Boy, I think we have enough "Or's" to rowe a Vicking ship. Thank you in advance for any information and please don't feel obligated to answer all. Thank you.

[geohui]

Thanks to all of you.

For the questionable results, we reported "Indeterminate" results to ABO and Rh typing and recommend repeat the ABO when the baby is around 9 months of age. But the company dissatisfied the results and need we give the explaination.

I think we will add "Indeterminate result due to present of mixed cell population cells" on the report.

For cord blood sample is Rh(D) typing is negative need to do Weak D test, so that mean we have treat the cord blood sample as blood donor sample and need to differentiate the sample is weak D or partial D phenotype?

[Liz]

Thanks to all of you.

For the questionable results, we reported "Indeterminate" results to ABO and Rh typing and recommend repeat the ABO when the baby is around 9 months of age. But the company dissatisfied the results and need we give the explaination.

I think we will add "Indeterminate result due to present of mixed cell population cells" on the report.

For cord blood sample is Rh(D) typing is negative need to do Weak D test, so that mean we have treat the cord blood sample as blood donor sample and need to differentiate the sample is weak D or partial D phenotype?

Is this private or public cord blood banking?

You may not have the ability to differentiate quantitative from qualitative weak D. So just perform the AHG phase and if it turns out negative then it is a true D negative; if it is positive then it is a weak D, either partial D or weak in quantity D. This means that if it is private banking for the same patient: no problem, if it is for public banking for another patient it is considered D positive. Then again at transplant with Bone Marrow ablation it should not matter so much.

Cord Blood is the baby’s blood. If, as Malcolm said, the ABO transferase enzymes are still weak, you did well to request another sample at 9 months. You may find a subgroup of A, or an AB... hmmm

Liz

[eltonsey]

Thank you for all