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??Antibody to High Incidence Antigen


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We received a sample from a 13 year old girl who presented at her GP with lethargy and dizziness. Her Hb was found to be 7.5 with a slightly raised bilirubin. She has no history of previous transfusion or medical condition. The results of the testing were as follows.Group B CcDee, DAT negative. Positive 2+/3+ with all panel cells by Ortho/Diamed IAT. Positive 4+ with all enzyme treated red cells using Ortho CAT. 2+ positive using LISS tube IAT. 4°C and RT screen negative.

Extended typing K- k+ ,Fya-b+, Jka+b+,Lea-b-, S-s+, M+N+, P1+ Lua-.

Does anyone have any explanation for these results in view of the fact that they are fairly certain she has never been transfused?

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Yes. We tested it against 2 Lea-b- and both were positive. Her auto was also negative. We have also asked the referring hospital to check the transfusion history with the patient and her parents and we will probably still test her against appropriate high incidence antigen negative cells.

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Is she post infection? could this be a PCH. Try doing a Donath Landsteiner

I was beginning to wonder about that too Anna (honest!).

Remember Rhona24, that you will need a clotted sample, and it may be better to use the Indirect Donath-Landsteiner Test, in case the young lady has used up all her available complement.

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[Most antibodies against high frequency antigens (if not all) are red cell stimulated.

Could this 13 yr old patient have an antibody that is reacting with one of the constituents

in Ortho's red cell reagent? Try testing the patient plasma with washed reagent cells

to see if the agglutination disappears?

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I was beginning to wonder about that too Anna (honest!).

Remember Rhona24, that you will need a clotted sample, and it may be better to use the Indirect Donath-Landsteiner Test, in case the young lady has used up all her available complement.

In my memory Donath-Landsteiner test pos antibody will not been tested by routine IAT technique, because it add against antigen in 4 degree C and in 37 degree C stimulate complements , but the antigen and antibody reaction is not tested in 37 degree C and we tested the complement on the cells.

I don't know if I say it clearly, my means is routine IAT has not the tip that D-L antibody needed .

I prefer it is a antibody against high frequency antigen.

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Anti P can be present without transfusions or pregnancy.

Malcolm,

What do you mean with "Indirect Donath-Landsteiner Test"? Is that a DL test with the adition of complement or do wash somewere?

I would not expect these strong reactions with a PCH

Edited by Rh-fan
typing error
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What about a Cold Auto-Antibody (such as Auto-Anti-I found secondary to certain pneumonias?) I know the information said that the patient's auto control was Negative, but we have seen cases like this where the auto control isn't Positive until it is incubated in the cold.

Donna

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In my memory Donath-Landsteiner test pos antibody will not been tested by routine IAT technique, because it add against antigen in 4 degree C and in 37 degree C stimulate complements , but the antigen and antibody reaction is not tested in 37 degree C and we tested the complement on the cells.

I don't know if I say it clearly, my means is routine IAT has not the tip that D-L antibody needed .

I prefer it is a antibody against high frequency antigen.

Yes, the thing is shily, that there has to be complement present in the first place. If you use an EDTA sample, then the Ca++, Mg++ and Mn++ ions that are required for complement activation are chelated by the EDTA. If, on the other hand, you use a clotted sample from the patient, where complement should be present, on occasions, the PCH is of a sort of chronic type, with, initially, low clinical levels of haemolysis, but the complement levels in the patient become very, very low, as complement is used up. "New", or "fresh" complement is not produced quickly enough for the D-L test to be positive. In other words, although anti-P may be present, when the test is put from 4oC to 37oC, there is insufficient complement there for haemolysis to take place - in other words, you get a false negative D-L test.

If you add complement (in the form of fresh serum from another healthy person, with no atypical alloantibodies), then the haemolysis takes place, and you get a true positive D-L test.

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Anti P can be present without transfusions or pregnancy.

Malcolm,

What do you mean with "Indirect Donath-Landsteiner Test"? Is that a DL test with the adition of complement or do wash somewere?

I would not expect these strong reactions with a PCH

Yes Peter, it is the addition of complement from a source other than the patient. This is because, in some circumstances, the patient's own complement is "consumed" in vivo, and you can get a false negative D-L test using their serum, because there is no "native" complement available to cause haemolysis at 37oC, even though there may be sensitisation by anti-P at 4oC.

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Malcolm,thanks for your reply. Maybe I express myself not clearly, sorry my English is not so good. I means the antibody is reacted with panel use IAT, but the D-L antibody will not been tested by IAT. I met a boy ,with anti-p, the antibody screening is neg, with C3 pos DAT only.

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