Why the DAT is positive after 24 hours?

[skyanto]

History: Mr. C.O. is a 63 years-old male with lymphoma.He is a politransfused patient.

Day one: Hb 7.8, PLT 3000, Bili.tot 2.13, Bili.Ind. 1.82.
Type and screen: DAT negative, IAT negative, Control group A+.
Transfused with 2 units of RBC (A+) and 1 unit of PLATELET (0+). All units were irradiated and filtered.Chills at the end of the transfusion.

Day two: Hb 8.2, PLT 10000 ,Bili.tot 2.31, Bili Ind. 1.98, LDH normal.
Type and screen: DAT positive 2+(diamed card), IAT negative, Control group A+,Monospecific : only IgG positive 2+ (diamed card), ELUITION negative( gamma elu-kit immucor and diamed panel 11 cells).

We have repeted the Day-one DAT and IAT and it was all negative.
We have cross-matched the two RBC units and they were compatible.
We have done a DAT of the two units and it was all negative.
We repeat on a new sample DAT and IAT : DAT positve 1+ IAT negative.
Transfused with 1 unit of RBC and 1 unit of Platelet.
Why the DAT is positive after 24 hours?
Gracias and sorry for my english...

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[aakupaku]

Test your eluate with A cell and B cell. You may have given platelet with high titer of anti-A.

[Steven Jeff]

Dear skyanto
I don't have an answer to your problem, but you have no reason to apologise for your English, it is excellent. Far better than my Italian!!! which is non existant.

Steve

[L106]

Aakupaku has given you good advice and the most logical possibility.

[Malcolm Needs]

Aakupaku has given you good advice and the most logical possibility.

I agree.

[skyanto]

We've tested the eluate with A1 and B cells.
The results are: positive 4+ with A1 and negative with B.
So the DAT is positive because in the group 0 PLATELET there were IgG anti-A in high titer.Do you have a procedure to do this titer?
Muchas muchas gracias a todos.

[Malcolm Needs]

We've tested the eluate with A1 and B cells.
The results are: positive 4+ with A1 and negative with B.
So the DAT is positive because in the group 0 PLATELET there were IgG anti-A in high titer.Do you have a procedure to do this titer?
Muchas muchas gracias a todos.

One way is to treat the plasma/serum/eluate with 0.01M dithiothreitol (DTT) at 37oC for about half-an-hour. This has the effect of disrupting the J-chain holding together the IgM molecule, by reducing some of the sulphydryl bonds. You then perform a titration, using the IAT at 37oC and a monospecific anti-IgG reagent.

Don't forget to use something like an auto-anti-I (which is going to be IgM) as a control.

Hope this helps.

[L106]

We've tested the eluate with A1 and B cells.
The results are: positive 4+ with A1 and negative with B.
So the DAT is positive because in the group 0 PLATELET there were IgG anti-A in high titer.Do you have a procedure to do this titer?
Muchas muchas gracias a todos.

Was there are reason that you wanted to do a titer, skyanto? Based on the results you described, you have investigated and identified what caused the patient's Positive Direct Antiglobulin Test. (There's really no reason that you must do a titer.)

Donna

[shily]

Malcolm, I don't think we need treat the blood with DTT to destroy IgM . Because IgM react in 37 degree C also have clinical significance in not ABO same type transfusion.
Skyanto do titer want to differ the high and low titer platelet, am I right?

[Malcolm Needs]

Malcolm, I don't think we need treat the blood with DTT to destroy IgM . Because IgM react in 37 degree C also have clinical significance in not ABO same type transfusion.
Skyanto do titer want to differ the high and low titer platelet, am I right?

Oh yes shily, you are right. It was just that skyanto wanted a method.