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Anti-D unusual variability


Jennifer G

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Has anyone seen an Anti-D go from negative to 2+ positive to negative? We had negative antibody screens on an elderly A Negative woman from 2012 through 2018. 8 RBCs were transfused during this time. In August 2018, the antibody screen was 2+ positive, Anti-D was identified, and she received 1 RBC. In April 2019, the antibody screen was negative on 2 different occasions. The possibility of the August 2018 specimen being the wrong patient seems unlikely since we use hand-labeled separately armbanded specimens. However, I have never seen a true Anti-D behave this way.

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It might be a transient autoanti-LW, only reacting with D+ cells.

Genuine examples of anti-D are usually more persistent than the situation you outline, but never say never. An elderly person's immune system may work in unpredictable ways. On a related tangent....if it is a "real" anti-D, I would wonder about the source of immunization - I'm assuming D- RBCs were transfused. You do not mention platelet transfusions.

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13 hours ago, exlimey said:

It might be a transient autoanti-LW, only reacting with D+ cells.

Genuine examples of anti-D are usually more persistent than the situation you outline, but never say never. An elderly person's immune system may work in unpredictable ways. On a related tangent....if it is a "real" anti-D, I would wonder about the source of immunization - I'm assuming D- RBCs were transfused. You do not mention platelet transfusions.

Totally agree exlimey, however, another question I have is, ws a DAT performed when the "anti-D" was detected?  I also have another suggestion, to go along with your question about platelets, and that is it could be that one of the units was from a donor with a DEL phenotype.  Unless elutions (obviously) or molecular techniques are used, this may never be known, but it is known that some types of DEL can cause primary stimulation, but that the anti-D produced in these circumstances is very weak.  As you say exlimey, as the patient is elderly (and ill), the patient's immune system could be compromised.

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1 hour ago, Malcolm Needs said:

Totally agree exlimey, however, another question I have is, ws a DAT performed when the "anti-D" was detected?  I also have another suggestion, to go along with your question about platelets, and that is it could be that one of the units was from a donor with a DEL phenotype.  Unless elutions (obviously) or molecular techniques are used, this may never be known, but it is known that some types of DEL can cause primary stimulation, but that the anti-D produced in these circumstances is very weak.  As you say exlimey, as the patient is elderly (and ill), the patient's immune system could be compromised.

Excellent points. The diagnosis, i.e., the reason for transfusion, might also give a clue. I also thought about RH-IG, but I can't think of a traditional use for that product in an elderly patient.

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Thanks for your replies! More info related to your comments... A DAT was not done at the time the antibody was identified, because the auto control in gel was negative. The patient has only received A Negative RBCs at our hospital (total of 9 at that time and 3 since then) and no platelets. She is a nursing home resident that was admitted for pneumonia, respiratory failure, and UTI. She has a previous history of coronary bypass surgery where she may have received blood products. Her platelet counts have always been in normal range 300-400s in our records. The DEL idea seems plausible to me. The Anti-D was relatively weak with reactions ranging from w+ to 2+.

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Another remote possibility: Passive anti-D from one of the transfused units ?

Most facilities are shy about transfusing red cells from donors with antibodies, but some of the savvy hospitals will get "favorable pricing" on Rh- units with anti-D. Since the Rh- unit (with anti-D) is typically going to an Rh- patient, the presence of the antibody is not usually a clinical problem, but may turn up as a laboratory anomaly. The amount of residual plasma in today's red cell products is very low, but a strong anti-D might show up post-transfusion and would probably only be seen be temporarily. You would have to look the timing of the transfusions and collection/detection of the anti-D-containing specimens. If you see a pattern, your blood supplier may be able to determine if any of the transfused units were from donors with anti-D.

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exlimey, again I agree, but it depends where Jennifer G is based.

NHSBT used to give out units of blood containing anti-D (and some other antibodies, as long as they were weak), but that is no longer so.  Since variant CJD raised its ugly head, we are no longer able to take blood from donors who have themselves been transfused (there are a few strange rules about when the blood was given, etc, but that is beside the point).  Because of this, and the fact that donors cannot be relied upon to be 100% honest (or simply don't know), so that we don't know if the antibody is as a result of a transfusion, a pregnancy or "naturally occurring", we destroy any units containing antibodies of any sort (with RARE exceptions), in case the antibody is the result of a transfusion, and it gets out into our untransfused inventory.

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1 hour ago, Malcolm Needs said:

exlimey, again I agree, but it depends where Jennifer G is based.

NHSBT used to give out units of blood containing anti-D (and some other antibodies, as long as they were weak), but that is no longer so.  Since variant CJD raised its ugly head, we are no longer able to take blood from donors who have themselves been transfused (there are a few strange rules about when the blood was given, etc, but that is beside the point).  Because of this, and the fact that donors cannot be relied upon to be 100% honest (or simply don't know), so that we don't know if the antibody is as a result of a transfusion, a pregnancy or "naturally occurring", we destroy any units containing antibodies of any sort (with RARE exceptions), in case the antibody is the result of a transfusion, and it gets out into our untransfused inventory.

Interesting. My perspective is from the USA. I assume then that the donors with detectable antibodies are permanently deferred ? That must put a hurt on the supply of Rh-.

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45 minutes ago, exlimey said:

Interesting. My perspective is from the USA. I assume then that the donors with detectable antibodies are permanently deferred ? That must put a hurt on the supply of Rh-.

Rh negative is more prevalent in Europe than US that European Blood Centers can afford to permanently defer donors with anti-D without hurting Rh neg supply? 

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22 minutes ago, Bb_in_the_rain said:

Rh negative is more prevalent in Europe than US that European Blood Centers can afford to permanently defer donors with anti-D without hurting Rh neg supply? 

This is very true.  There are certain areas of Europe (in particularly the Iberian Peninsula) where the percentage of D Negative individuals within the native population reach 25%.  This is all to do with enclaves where D Negative Palaeolithic people took refuge during the last Ice Age (about 24, 000 to 16, 000 years ago).  Other areas where this happened were the Balkans and Ukraine.

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