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Positive crossmatch


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Patient has Anti Jkb antibody therefore x match 4 units with Jkb negative blood but while performing xmatch it was found all the units were positive BUT Auto is negative.  What are the possible reasons for this?

Edited by gagpinks
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  • gagpinks changed the title to Positive crossmatch

That's what I thought it could be low-frequency antibody or another antibody masking under Jkb. But my senior is saying is due to high frequency antibody   but my argument is if it is HFA, panel should be positive with all cell lines. Please correct if I am wrong 

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Well, I would almost agree with you, except that it is not necessarily a low-frequency antibody; it is MUCH more likely to be an antibody directed against a low-frequency (low prevalence) antigen, and some of these (for example, anti-Wra) are found quite regularly, if you are daft enough to go looking for them!!!!!!!!!  You are, however, absolutely right in saying that, if it was an antibody directed against a high-frequency (high prevalence) antigen (for example, anti-Vel) then there would be agglutination with all the panel cells (with possibly one being negative, just be sheer chance).

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2 hours ago, exlimey said:

What is the ABO group of the patient and of the crossmatched units ?

My initial thought is check for ABO compatibility, which is what exlimey is suggesting. How was the Jka antigen testing performed? Were controls run and did they work? Also, perform a DAT on the units. If they are DAT positive, your crossmatches are invalid. I doubt that would be the issue though. 4 donors all having positive DAT's? If you had a clear anti-Jka identified, and all other antigen groups ruled out homozygously, there is no reason the units should be XM incompatible if they are ABO matched.

Edited by jayinsat
correct spelling error.
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  • 2 weeks later...

How are you doing your crossmatch?  This could, as Arno said above, be an anti-buffer reaction - or it could be a cold antibody that's got enough time to stick on to the red cells before they get to 37°C.  Can't be an antibody against a low-frequency antigen - not with 4/4 being positive.  I would also double check that the blood bags really are Jka- and of the correct ABO group.  You haven't answered the question about the patient's blood group.........

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