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klsmith

More Antibody I.D. Questions

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Hi All,

This post actually relates to my very last post about antibody I.D.'s. So if my SOP states that I am not to re-identify previously known identified antibodies (this meaning only setting up panel cells that are negative for the known antibody) then wouldn't I miss something like say, an anti-f? So for example, lets say that I have a patient that I initially identify what looks like an an ant-e (but in all actuality it is an anti-f!). Then 8 months later, that same patient comes back to my facility, has a type and screen done, and I see that the antibody screen is positive, and that we have previously identified an anti-e. So, per my SOP, I only set up e negative cells on my panels. Wouldn't I miss the anti-f???

 

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In this context "re-identifying" an antibody refers to documenting you have 2 cells (or 3 depending on policy) that are positive for that antigen and 2 (or 3) cells that are negative for that antigen plus testing the patient for the corresponding antigen. Once the antibody is identified "re-identification" is not needed but one positive cell shows it is still reactive if all else is ruled out. So for example I will choose select cells that are negative for previously identified antibodies that will allow me to rule out all antibodies I am required to by policy. I will also ensure there is at least one cell positive for that antibody to see if it is still reactive (closes the work-up with a bow). I will also double check all positive cells (probably on the screen) to see if there are any other antigens that are not ruled out, for example Jsa, Kpa, Lua, V, f etc., if there are then another cell is needed to rule it/them out. So on a practical approach: you run the screen, chose cells to rule out all clinically significant antibodies spelled out in your policy and issuing non-reactive units covers the rest. If you are still concerned I suggest you closely read your policies and SOPs to ensure, to your satisfaction, that it makes sense and nothing was missed. There are many threads on this site delving into the more esoteric, unusual and complicated antibodies and how different transfusion services deal with them and why. With respect to your example: an e negative unit will be f negative as the f antigen is only expressed if both the c and e antigen are present AND they are in the cic position; therefore either c negative or e negative units (patients) will be f negative.

Hope this helps.

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I do apologize Ensis01, but I am not picking up what you are putting down!  Not all screen cells are positive for the f antigen. Aren't all little f cells positive for little e? I guess i am just not understanding what you are trying to say......

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3 hours ago, klsmith said:

Hi All,

This post actually relates to my very last post about antibody I.D.'s. So if my SOP states that I am not to re-identify previously known identified antibodies (this meaning only setting up panel cells that are negative for the known antibody) then wouldn't I miss something like say, an anti-f? So for example, lets say that I have a patient that I initially identify what looks like an an ant-e (but in all actuality it is an anti-f!). Then 8 months later, that same patient comes back to my facility, has a type and screen done, and I see that the antibody screen is positive, and that we have previously identified an anti-e. So, per my SOP, I only set up e negative cells on my panels. Wouldn't I miss the anti-f???

 

I would be much more concerned if it were the other way around (i.e. you detected an anti-f, but missed an anti-e).  You are correct in saying that all red cells that are f Positive are also e, but not all e Positive red cells are f Positive.  If you either miss an anti-e, or misidentify an anti-e as an anti-f (possibly because of dosage), then there is the danger that an e Positive unit may appear compatible when it is not.  However, more importantly, an anti-hrS is often misidentified as an anti-f, and an anti-hrB is often misidentified as an anti-Ce or an anti-C+e.

Not for one minute am I suggesting that your skills in antibody identification are not "up to scratch", but, working in a Reference Laboratory in London, with its wonderful mixture of ethnicities, I have seen too many antibodies misidentified by hospital laboratories.  This is not their fault - it is just that they do not see some of these specificities often, and they do not have the required rare reagents.

I would say, therefore, that it never hurts to test at least one cell each time that is positive for the cognate antigen to prove the suspected specificity of the antibody.

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6 hours ago, klsmith said:

I do apologize Ensis01, but I am not picking up what you are putting down!  Not all screen cells are positive for the f antigen. Aren't all little f cells positive for little e? I guess i am just not understanding what you are trying to say......

My main point I was trying to make is that your policy/SOPs should explicitly define what you MUST rule out, like anti-e and what you rule out if it happens to be present on the cell. To put it another way if a patient has a negative screen but none of the screen cells have the f antigen, does your policy require you to find a select cell that does? 

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Klsmith’s original question is regarding concern of missing an anti-f if the patient has an anti-e. I am trying to make the points (and failing it seems) that firstly giving e neg units side steps the f issue. Secondly his blood bank policy should state the normal clinically significant antibodies that need to be ruled out and how to deal with the others. This site is a great way to clarify any confusion created with respect to “the others” or if the policy or logic is not clear. 

 

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34 minutes ago, Ensis01 said:

Klsmith’s original question is regarding concern of missing an anti-f if the patient has an anti-e. I am trying to make the points (and failing it seems) that firstly giving e neg units side steps the f issue. Secondly his blood bank policy should state the normal clinically significant antibodies that need to be ruled out and how to deal with the others. This site is a great way to clarify any confusion created with respect to “the others” or if the policy or logic is not clear. 

 

I understood your comments Ensis01, and I don't entirely disagree with what you said, but I did expand to try to explain why I (I hope, politely) disagree.

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Malcolm,

First off, I actually do feel like you are telling me that my antibody ID skills are not "up to scratch." If you didn't think it, then you would not have even said anything of that nature at all (subliminal thinking coming out maybe?). I am not an IRL Tech like you are (mark my words, I will be eventually), and my resources are not as extensive as yours either by any means. I do know however that we had a patient that had been transfused a month and a half ago, and now appears to have an Anti-C as well as an Anti-e. The last time he had a crossmatch done, he appeared to have an anti-D. He is Rh positive, and not receiving any kind of passive anti-D (we thought maybe an anti-LW?). That being said he got 2 units of O neg in August, but we phenotyped him anyway, just to see if anything would be negative.  His phenotype indicates that he is probably an R1R2. I know his phenotype is not actually valid, since he has been transfused, but we were looking also to see if there were mixed field reactions in the Rh phenotyping gel cards, and there were none. It was a straight 4+ across the board.  Anyway, the eluate uncovered a 1+ reaction on cell #3 of the screen (its a 3 cell screen, little f is positive on cell #3, in addition to the e antigen.) The original screen only reacted on cell#1, which fit an anti-C). Our concern is that he may have actually made an anti-f If he is in fact an R1R2), from receiving the O neg units. The reason that we are unsure of anti- f or anti-e definitively is because the "supposed anti-C" masks all cells on all panels we have that are e positive, f negative.  We have no clue about the anti-C, so that is why we sent it to our reference lab. The anti-C just doesn't make sense and the whole work-up became confusing. Our reference lab suggests that when we suspect an anti-LW, that we give Rh negative units. But if there is a potential ant-C and anti-e or f, then what do you transfuse the patient with?? Rh neg units will be positive for the e antigen 98% of the time! No, I am not knowledgable about anti-hr(s) or anti-hr(b). I look to experts like you to inform me, just saying.....

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4 hours ago, klsmith said:

First off, I actually do feel like you are telling me that my antibody ID skills are not "up to scratch." If you didn't think it, then you would not have even said anything of that nature at all (subliminal thinking coming out maybe?).

klsmith PLEASE believe me when I say that I was not in any way suggesting that your antibody ID skills are inferior to anyone else, including people who work in Reference Laboratories.  In the UK, the individuals who work in even the smallest hospital laboratories take exactly the same examinations as the individuals who work in the Reference Laboratories, and so they have PROVED that their skills are identical.  The only differences would be that those working in a Reference Laboratory would be more experienced dealing with samples exhibiting the rarer antibodies, the rarer antigens and those containing complex mixtures.  The key thing is though, that they have access to many more rare reagent red cells and antisera, and, possibly other reagents, such as recombinant red cell proteins, and techniques, such as genotyping.  Apart from anything else, as we have not met, I would hardly be in a position to either praise, or to criticise your antibody ID skills.

Turning to your own Reference Laboratory, I am, to say the least, a little surprised that they did not go further and actually prove that an anti-LW is present.  True LW Negative red cells are rare (D Negative red cells are NOT LW Negative), but they are not unknown.  If they suspected anti-LW themselves, and they did not have the reagents necessary to either prove or disprove the specificity (true LW Negative red cells and anti-LW), then, in my opinion, they should have referred your sample "further up the line" to a Reference Laboratory that actually does have these reagents, rather than just leaving the specificity "up in the air", as it were.  They should also have given you advise on what blood to transfuse.  If you and your Reference Laboratory both think that there is a genuine anti-e, and/or an anti-f and/or an anti-C/anti-Ce present, in addition to the anti-LW, you do have a problem.  I would suggest that, short of giving Rhnull blood, which is, of course, incredibly rare, the safest you could transfuse is r"r" (dcE/dcE), which would be both C /Ce Negative and e/f Negative, while expressing the LW antigen extremely weakly, but such donors are also rare (although nowhere near as rare as Rhnull).

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So Malcolm,

Tell me more about anti-hr(b) and anti-hr(s). As much as you can if you dont mind.

Thank you!

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Easier said than done Kelly; even the likes of Geoff Daniels admit that they do not totally understand hrS and hrB.  This is mostly because they are both (essentially) mutations within the RHCE gene, but are often thought of as e-like antigens - which, in itself is not true, as most also involve weakening of the C or c antigen too.  In addition, however, before the days of molecular work, many antibodies to these antigens were misidentified as anti-hrS or anti-hrB, when they were either the other way around, or, indeed, were other specificities altogether, and yet are still misidentified even today, if molecular work is not carried out.

All that having been said, I have put together a PowerPoint lecture on the subject to try to explain what is going on.  Unfortunately, it is far too big to upload on to here, but if you could send me a private message, either on here, or by FaceBook, I would willingly send it to you.

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1 hour ago, Malcolm Needs said:

All that having been said, I have put together a PowerPoint lecture on the subject to try to explain what is going on.  Unfortunately, it is far too big to upload on to here, but if you could send me a private message, either on here, or by FaceBook, I would willingly send it to you.

@Malcolm Needs, if you want to email it to me, I'll get it uploaded in the Library here.

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