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Alisun

Tk activated red cells, DAT neg, serious haemolysis, ? cause

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Patient with bowel issues presented with serious haemoloysis, Hb dropped to below 60g/L.  Frank haemolysis apparent but DAT was completely negative, Ab screen/IAT and enzyme IAT panel neg, auto negative, eluate neg vs panel by IAT.

Consultant Haematologist suggested performing T activation studies.  Patient was found to be Tk activated, but Tk activation not associated with haemolysis.

I have heard on the grape vine that Tk activation is associated with acquired B phenotype.  Patient was group A with anti-B. Current ABO typing reagents do not detect acquired B, so we do not know whether this patient had acquired B.

Hypothetically, could haemolysis occur with acquired B? Could the patient's naturally occurring anti-B haemolyse the 'acquired B' red cells???

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1 hour ago, Alisun said:

Hypothetically, could haemolysis occur with acquired B? Could the patient's naturally occurring anti-B haemolyse the 'acquired B' red cells???

Group A individuals are the only people who can have the acquired-B phenotype, and the bowel issues would fit.  I have seen a few of these during my working life, but in my limited experience, the anti-B in the plasma of such an individual does not react with the autologous red cells.

Interestingly, there are several bacteria that cause the acquired-B in slightly different ways (but all by deacetylation, in various ways, of the A antigen), however, if an individual gets the acquired-B caused of infection by one strain of bacterium, the anti-B in their plasma will not only not react with their own red cells, but will also not react with red cells from another individual, who has the acquired-B phenotype caused by the same strain of bacterium, but will react with the red cells of another individual, who has the acquired-B phenotype caused by a different strain of bacterium (and vice versa).

Did you carry out the DAT and the lectin panel yourselves?  If so, did you use a monoclonal anti-IgA?  I have seen a very few cases of AIHA with frank haematuria caused by an IgA auto-antibody.

The other thing is, what was the patient's underlying pathology, and had he been put on any therapeutic drugs prior to this haemolysis (I am wondering, completely vaguely, in terms of drug-induced haemolysis, which can sometimes be DAT negative)?

Edited by Malcolm Needs
Spelling and various other basic mistakes!

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