Previously demonstrating antibodies

[MEG]

Is it important to prove if a previously demonstrating antibody is still demonstrating? Should a rule out of this antibody be done?. Does it even matter because you have to give antigen negative for previously demonstrating antibodies anyway? The antibody is a big C, patient is 56. If anyone can provide me with literature that references this that would be so great!!!

[Malcolm Needs ☆]

Is it important to prove if a previously demonstrating antibody is still demonstrating? Should a rule out of this antibody be done?. Does it even matter because you have to give antigen negative for previously demonstrating antibodies anyway? The antibody is a big C, patient is 56. If anyone can provide me with literature that references this that would be so great!!!

We would always do so, but there is no particular reason (apart from the fact that we are a Reference Laboratory, and that is how we do things). In certain cases though (and here, I am thinking in particular of anti-Jka and also of Lewis antibodies in pregnancy) the antibody "fades" very quickly, and even the most ardent serologist can no longer demonstrate the antibody. In the case of anti-Jka, I would ALWAYS give Jk(a-) blood, even if I could not demonstrate the antibody. Nasty little critters anti-Jka's!.

[John C. Staley]

Our philosophy was "once it's there it's always there" so we did not go to any great lengths to confirm we could still find it. I believe it was the University of Michigan Blood Bank where I first learned that if the antibody screen indicated the presense of no new antibodies and the antigen negative units were AHG crossmatch compatible there was no need to perfom an antibody ID panel on the new sample. The AABB Standards can be read to support this method.

The object is not to prove the previously ID'd antibody is still there but to determine if anything new has arrived.

[Malcolm Needs ☆]

Yes, I'd go along with John completely; we go way over the top sometimes.

[MEG]

Thanks. I truly appreciate you taking the time to answer my question.

[Mary**]

:handshakeWe do the same. We result the antibody identification with the response "No additional antibodies detected" if that is the case.

[BSIPHERD]

The only reason that we occasionally run cells to determine if the antibody is still reacting is to determine if we can use the patient's plasma to screen units, then only antigen type the units that don't react. Particularly these days with the high cost of reagent typing serum.

[Liz]

The only reason that we occasionally run cells to determine if the antibody is still reacting is to determine if we can use the patient's plasma to screen units, then only antigen type the units that don't react. Particularly these days with the high cost of reagent typing serum.

I don't know if you should do that for your selective phenotypes, you would need validation etc... and may miss something, I prefer a bit of expense but to be safe. Ah, but anyhow, you are repeating with reagents, so it sounds alright.

About the AbID, Mindy:

AbID must be performed in case new Abs have been formed.

[jdo1217]

With a historical antibody that was demonstrating the last time we tested, we run a selected cell panel consisting of one cell positive for the known antibody and enough cells to rule out everything else. If the antibody stops demonstrating, we go back to our 2-cell screen to save money. Antigen-negative units are crossmatched via AHG.

[tbostock]

If a patient has a previously identified antibody, and the antibody screen is negative, (after we yell "WOOHOO!"), we antigen type units and perform Coombs' crossmatches. If the antibody screen is positive, that essentially "proves" that it is still demonstrating, so we just do selected cell panels to look for new antibodies. Like John Staley says above, no need to keep identifying the same antibody, since you are going to honor it forever.

[jayinsat]

if the patient is a frequent flyer or if the antibody screen pattern reacts consistent with the historical antibody, I will often test a select cell (rule out) panel, running only cells negative for the antigens of the known antibody. I believe this helps in identifying anything new as the reactions from the known antibody won't be there.

[tbostock]

Mindy, in the Technical Manual, 16th edition, page 471, next to last paragraph, it gives an example of what to do with previously identified antibodies.