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anti-Lewis a,b


SMILLER
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We are in the process of re-thinking our approach to how we deal with the Lewis antigens.  Between our pathologist, our blood-supplier lab, and our own thoughts on the subject, our BB coordinator is about ready to blow her brains out.

There are essentially two situations; one in which a patient is currently making anti-Lewis a (or anti-Lewis b), and one in which the patient has a history of the Lewis antibody in question, but currently has a negative antibody screen.

My question then is: what, if anything, do you routinely do in these two situations?

Thanks, Scott

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32 minutes ago, Dansket said:

If current antibody screen is positive and Lewis antibody identified, do immediate-spin and anti-igG crossmatches, issue crossmatch-compatible random donor units.  If current antibody screen is negative and there is a history of Lewis antibody, do Computer Crossmatch with random donor units.

Not too different from what we are currently doing, except when there is only a history of anti-Lewis with a current neg screen, we are required to get Lewis antigen negative units form our blood supplier (they do get annoyed about these types of requests),  

Scott

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16 hours ago, SMILLER said:

Not too different from what we are currently doing, except when there is only a history of anti-Lewis with a current neg screen, we are required to get Lewis antigen negative units form our blood supplier (they do get annoyed about these types of requests),  

Scott

In the UK, we give cross-match compatible blood in both situations.  NHSBT do not give out typed blood for Lewis antibodies.

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16 hours ago, bbslm said:

For both situations we would give IAT and immediate spin crossmatch compatible blood, would not worry about finding antigen negative units.

Which seems logical to us who are working on the bench in the Lab.  Our reference lab agrees with us.  However, our pathologist has other ideas (he seems wary about that "one patient" who produces IgG anti-Lea). 

What it looks like we are going to be doing in the future is: if there is a history and the current screen is negative, we carry crossmatches through AHG from out regular donor supply.  If the Lea is showing up, and the situation is not "emergent', we have to request confirmed Lea negative units from our blood supplier.

With this proposed policy, I was also wondering what the likelihood is of inducing a detectable Lea antibody response for the first case, assuming the screen-negative recipient gets a few Lea positive units.

Thanks for your responses    -Scott

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Is your pathologist also worried about all of the antibodies to low-incidence antigens that aren't present on your screening cells?  Although I've not heard reports of any clinically significant transfusion reactions to those, they are also theoretically possible and missed by not doing AHG crossmatches for all units.  Maybe some information like this could be used to "calibrate" the pathologist's worry meter.  The fact that the Brits have not had any reports of patient impact to make them change their national policy might serve as a sufficient "research study".  Nothing in this business is perfectly safe.

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3 hours ago, SMILLER said:

Which seems logical to us who are working on the bench in the Lab.  Our reference lab agrees with us.  However, our pathologist has other ideas (he seems wary about that "one patient" who produces IgG anti-Lea). 

What it looks like we are going to be doing in the future is: if there is a history and the current screen is negative, we carry crossmatches through AHG from out regular donor supply.  If the Lea is showing up, and the situation is not "emergent', we have to request confirmed Lea negative units from our blood supplier.

With this proposed policy, I was also wondering what the likelihood is of inducing a detectable Lea antibody response for the first case, assuming the screen-negative recipient gets a few Lea positive units.

Thanks for your responses    -Scott

Does your Pathologist not understand that Lewis antigens are not intrinsic to the red cell membrane (in fact, in all probability, if they were discovered now, they would almost certainly NOT be recognised as red cell antigens by the ISBT).  As such, even the small amount of plasma contained in packed red cell units is sufficient to adsorb out most of the patient's Lewis antibodies in vivo, during the actual transfusion.  Those transfused red cells that survive in the circulation (i.e. about 100%) will very quickly assume the Lewis type of the recipient.  He or she might like to read Sneath JS, Sneath PHA.  Transformation of the Lewis groups of human red cells.  Nature 1955; 176: 172, as this may serve to stop the worrying.

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17 minutes ago, Malcolm Needs said:

Well, I could give a couple of more recent ones, concerning Lewis types after stem cell transplantation, but that would seem egocentric!

And back in the days before you retired, you would have given us a typical comprehensive (and enlightening) review of the Lewis system!

Scott

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In my 40 years of practice since finishing training we have never ordered Lewis negative units for transfusion.  We give crossmatch compatible (IgG/37 degrees) units, although

even that is probably overkill.  Lewis antibodies do not cause hemolytic transfusion reactions with IgG/37 degree non-reactive units.  Your pathologist is perhaps not a full time

transfusion medicine physician?  Not that there's anything wrong with that :).

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  • 1 year later...
On 11/13/2018 at 11:46 AM, SMILLER said:

Not too different from what we are currently doing, except when there is only a history of anti-Lewis with a current neg screen, we are required to get Lewis antigen negative units form our blood supplier (they do get annoyed about these types of requests),  

Scott

.    

Edited by R1R2
just read the rest of the posting. Maybe have the blood supplier medical director call you medical director.
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