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SMILLER

Picky anti-C?

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We had a patient, 30-year-old female, B pos, who showed up last week with an anti-C along with a few equivocals.   When it was time to repeat the T&S (and antibody ID) a few days later, we went ahead and set up a panel along with the screening cells, since we already knew there was an atypical antibody that would show up.  To our surprise, the screen was negative (Ortho manual gel).  The panel reacted as expected, pretty good 1+ reactions for the C, with a few equivocals.  

The second specimen's screen was with a different lot of screening cells.  We also tested with the original specimen's lot number of screen cells, and 3% tube screening cells -- those reacted as expected for an anti-C.

Kinda odd.  The newer screening cells were checked with another patient who makes anti-C - that reacted as expected also.  Its just the one patient with the one lot of screening cells that did not react.  Kinda odd.

Scott

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Most antibodies identified as "anti-C" are, in reality, a mixture of anti-C and anti-Ce (with the anti-Ce portion often being in the majority).  This is because many of the antibody producers are R2R2, sensitised by the DCe or dCe haplotype - not all, of course, but many.  According to my mentor, Joyce Poole, this was true even of monoclonal antibodies that are considered to be "anti-C".  This is why you often get weak reactions with RzRz red cells with most examples of anti-C.

As you are getting variable reactions with your panel cells, it could be that you have a rare example of a pure, monospecific anti-C, or an "anti-C", made in an R2R2 or R2r individual, who has been who has been sensitised by a DCE or dCE haplotype, and that you have an "anti-C" that is a mixture of true anti-C and anti-CE.

All that having been said, I can't see that the above information would necessarily give a reason for your patient's odd reactions, but it might just be one of several reasons.  What those other reasons may be, I don't know!

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I should have mentioned, the original screening cell that did not react with was listed as R1R1, while the patient reacted fine with R1R1 cells on the other set of screening cells and with the panel cells.  So, kind of odd.  We did call Ortho but they had nothing to add about the situation.

Scott

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Hmmmm.  Unless that particular cell is actually a DCe/--- (which I doubt, as they are disappearingly rare), and so has hemizygous expression, where homozygous expression would be expected, this is a bit of a mystery - unless the RHCE*Ce gene contains either a homozygous mutation, or a double heterozygous mutation - but again, this would be exceedingly rare.

I'll keep thinking, but hope someone else comes up with a more realistic reason!

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On 7/26/2019 at 7:18 AM, SMILLER said:

We had a patient, 30-year-old female, B pos, who showed up last week with an anti-C along with a few equivocals.   When it was time to repeat the T&S (and antibody ID) a few days later, we went ahead and set up a panel along with the screening cells, since we already knew there was an atypical antibody that would show up.  To our surprise, the screen was negative (Ortho manual gel).  The panel reacted as expected, pretty good 1+ reactions for the C, with a few equivocals.  

The second specimen's screen was with a different lot of screening cells.  We also tested with the original specimen's lot number of screen cells, and 3% tube screening cells -- those reacted as expected for an anti-C.

Kinda odd.  The newer screening cells were checked with another patient who makes anti-C - that reacted as expected also.  Its just the one patient with the one lot of screening cells that did not react.  Kinda odd.

Scott

Are you using solid phase by any chance? We have seen solid phase does that, since a lot of our hospital used solid phase method. When that happened, we usually look for antibodies using PeG Tube method or by testing ficin-treated cells. We were usually able to find the suspected antibod(-ies) except for Kidd antibodies. You may be looking at some method-dependent antibody? Anti-C in your 2nd sample may be stronger than that in your first sample? 

What is the patient's ethinicity? Is the patient e- or e+? I am also thinking about anti-Ce like antibodies if you see this anti-C reacting stronger with e+ cells than e- cells. 

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The patient is long gone.  But the same method -- manual gel -- was used for both the screening cells and the panel cells.  As I mentioned, the reagent cells were both all R1R1 (but from different donors)--yet only the cells from the one screening set was negative.

Had to be something wrong with that particular cell and that particular patient.

Scott

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6 minutes ago, StevenB said:

Just curious...did you serologically confirm the Rh phenotype of the reagent cell in question?

Yes.  At least we got a reaction with anti-C reagent.  Likewise, that particular cell reacted with another patient who was producing ant-C. 

Scott

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We've seen a patient like that. We ID'd a clear cut but weak anti-C w/ solid phase on one specimen, not there with the next specimen, back again w/ a 3rd specimen, We discovered that she had been transfused somewhere else between our visits. That lab used gel and they had not detected the anti-C. We suspect that she received C positive blood, which pushed her titer up again.

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4 hours ago, AMcCord said:

We've seen a patient like that. We ID'd a clear cut but weak anti-C w/ solid phase on one specimen, not there with the next specimen, back again w/ a 3rd specimen, We discovered that she had been transfused somewhere else between our visits. That lab used gel and they had not detected the anti-C. We suspect that she received C positive blood, which pushed her titer up again.

Ya.  If I recall correctly, this patient had a strong 1+ reaction with all C pos cells, except for that one screening cell.  That one screening cell otherwise reacted normally with anti-C from both reagent and another patient.  So just have to forget about this one.

Scott

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On 9/18/2019 at 8:06 AM, SMILLER said:

The patient is long gone.  But the same method -- manual gel -- was used for both the screening cells and the panel cells.  As I mentioned, the reagent cells were both all R1R1 (but from different donors)--yet only the cells from the one screening set was negative.

Had to be something wrong with that particular cell and that particular patient.

Scott

Maybe if you have ficin or papain, you can treat the C+ cells that were originally negative to see if your strange "anti-C" pops up? If the patient is an African American, I would consider the presence of variant RHCE gene. 

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