AB mom with 1+ anti-A reverse

[LilBill]

I recently had a woman come into labor and delivery who forwards are as listed

A-4+ B-4+

Reverse

anti-A-1+

Anti-B-0

I have subsequently ordered a new type and screen to get the same results. I suspect one fo two things she is a A subgroup B patient or she has been sensitized during pregnancy to some other A subgroup. I am using tube method and checked for rouleaux. Does this seem feasible any suggestions to resolve this?

[clmergen]

AB patient with an Anti-A1 is what I would suspect. I would test the patient plasma with A2 cells, test patient cells with A1 Lectin and run an IS screen to rule out other cold reacting antibodies.

[L106]

I would perform an Antibody Screen using all of your routine phases, not just the Immediate Spin phase. I just think that is a good, standard practice before I would report out any antibody identification.

[heathervaught]

If the patient was an A subgroup, would the cells react that strongly with the anti-A reagent? I would think that a more likely scenario is that the patient has an IS-phase alloantibody, such as anti-M, that is reacting with the A cells. You can (1) just try another lot of A cells to see if you get the same result, or (2) screen some of your inventory for an M-negative unit.

If you think that your antibody is anti-A1, then you need to confirm it with at least showing reactivity with one more example of A1 cells, and lack of reactivity with one A2 cell, and one O cell. This will get you at least to a 2+2 level of confidence that the antibody is anti-A1.

[Malcolm Needs ☆]

I agree that it could be an anti-M, a Lewis antibody, anti-P1 or the like, but I think that it is far more likely to be an anti-A1.

A2 and A2B red cells react very strongly with monoclonal anti-A reagents (far stronger than the old polyclonal, human-derived anti-A reagents, when it was usually quite easy to distinguish an A1 from an A2). I agree that putting the lady's red cells up against Dolichos biflorus would show if she is A1B or A2B, but even if she is A2B, you would still need to "prove" the specificity of the antibody as anti-A1, as suggested by other posters.

Whatever the specificity proves to be, I doubt very much indeed that it has anything to do with this lady's pregnancy (from the point of view of the original stimulation), although the immune system of a pregnant lady may well allow the antibody to be "stronger" during pregnancy and in the peri-partum period.

Please would you keep us informed of what you discover?

Thanks.

:):)

[heathervaught]

So can I change my answer? Hindsight is always 20/20! To investigate this discrepancy, you need to identify the antibody. You have an antibody that is reacting at IS phase with an antigen that is present on the A reverse cells. This could be an anti-A1, but you have to prove it (see above) because it could also be an antibody to another antigen that is present on the A reverse cells, such as anti-M.

Edited May 27, 2010 by heathervaught
poor grammar

[LilBill]

I apologize for the delay in communication. I am at a small hospital in the transfusion medicine department. We send out all of our positive antibody screens. I received the results of the workup yesterday.

I should have mentioned that I performed both gel and tube screens and both were negative.

I also attempted reverse typing with a different lot # of A1 cells. I have the same results.

The antibody identification results from our reference lab showed that she has anti-A1 and types as A2B.

Unfortunately, she gave birth before we could get those results. I had a fear that the baby could be A1B if the father was A1. The father was actually O pos.

I later typed the baby as B pos. Phew!

Currently our policy is to ask pregnant women with an antibody to have an antibody titer done throughout the pregnancy. Does anyone have policies for anti-A1 titers for pregnant women? I imagine it should only be done if anti-A1 reacts through AHG phase. Thanks for your suggestions!

[Malcolm Needs ☆]

I

Currently our policy is to ask pregnant women with an antibody to have an antibody titer done throughout the pregnancy. Does anyone have policies for anti-A1 titers for pregnant women? I imagine it should only be done if anti-A1 reacts through AHG phase. Thanks for your suggestions!

Fear not. Even IgG anti-A1 (which, in itself is incredibly rare) has never been implicated in clinically significant haemolytic disease of the newborn.

This is partly due to the fact that the transferase enzyme that creates the A1 antigen is not functioning to its full extent at birth, and so the number of A antigen sites per red cell is quite small compared with the number of A antigen sites per red cell for an adult.

:D:D:D:D

[L106]

Quite true, Malcolm. (Therefore, I would not advocate titering the Anti-A1.)

[LaraT23]

It is so strange that I am reading this today. I had a patient who is Apos historically come in last night with a broken hip. The surgeon ordered a 2 unit cross match. When my tech got the specimen and did the ABO, she found that the Acell was 2+ reactive. The antibody screen was negative so she just crossmatched some O cells and one was 2+ incompatible. We did transfuse her in March, but the screen remains negative.

My theory is that we have a low incidence that just happens to be present on the A cell and the O cell she tried to crossmatch. I sent it out my reference lab for an enhanced antibody screen and select cells, so we shall see what they say!

Just odd how I have the same thing today.

[LaraT23]

Mine turned out to be Anti-P1 by the way. I did a tube antibody screen at 4 degrees and there it was. The ref lab sent P1 negative units which I am sending back to credit. No need really.

[lbrolliar]

I have a patient today that is historically an ABPOS, we typed her in April of this year. She received 2 platelets (one AB and the other O). Today she front types as AB but has 3+ A1 cells. If she has a sub group, wouldn't we have seen this previously on the original work up in April? She's here for another platelet transfusion, would you avoid giving A typed platelets in this situation?

[Malcolm Needs ☆]

I have a patient today that is historically an ABPOS, we typed her in April of this year. She received 2 platelets (one AB and the other O). Today she front types as AB but has 3+ A1 cells. If she has a sub group, wouldn't we have seen this previously on the original work up in April? She's here for another platelet transfusion, would you avoid giving A typed platelets in this situation?

Well, I would suggest that the first thing you do is to type the patient's red cells with Dolichos biflorus, and if she is negative with that, then prove that the antibody is actually anti-A1 (it may be some other "cold" reacting specificity like anti-M, anti-P1, etc).

The answer to your first question is NO, you would not necessarily have noticed it. Monoclonal reagents are incredibly strong compared with the old polyclonal, human-derived antisera of yesteryear, and work very well indeed with quite a lot of subgroups (be they A, D or many other specificities - as long as the specific epitope against which the antibody has been raised).

The answer to your second question is also NO. The ABO antigens are extremely weak (there is still some dispute as to whether they are intrinsic to the platelet membrane or just adsorbed from the plasma - it depends on which papers in the literature you believe!), but a "cold-reacting" anti-A is not going to cause platelet destruction. If there is a lower than expected platelet increment, look for other reasons such as HLA antibodies.

On the other hand, giving group A platelets to a group O patient, with a high-titre anti-A can lead to platelet destruction.

:):)