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Brenda Hutson

Anti-f

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If Immucor has removed f designations from the panel, we will have to identify them as we have been with G, which was never designated on the panel. If someone misidentifies an anti-f as an anti-c, at least they will be giving f negative blood by giving c negative blood. SInce we don't have f antisera, we usually give c negative blood to patients with anti-f anyway.

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Did you mean to say anti-C; or anti-c? You may very well have been discussing C; just clarifying since there was much discussion about f and the relationship to c.

Brenda

Yes, I think we are discussing the clinical significance of anti-C, but only in relationship to the post in the thread about why anti-f seems to be less clinically significant than, say, anti-D or anti-c. We aren't trying to hijack the thread - just broaden it in terms of clinical significance if anti-f is identified or, come to that, mis-identified as anti-c.

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Right, but as I mentioned before, I have seen an anti-f identified as many things (including Jka at 2 different Facilities)! If I knew it would always be misidentified as an anti-c, I would not be as concerned; but I know from experience that this absolutely is not the case.

When people are inexperienced in antibody identification, they often look for a pattern rather than going through the steps of ruling out first; seeing what is left; and working from there. And on any given panel, who knows which Antigen will be present on most of the f+ cells (besides c). In an ideal world, such people would not be working in the Transfusion Service, but if you find a way to accomplish that, let me know!

Brenda

If Immucor has removed f designations from the panel, we will have to identify them as we have been with G, which was never designated on the panel. If someone misidentifies an anti-f as an anti-c, at least they will be giving f negative blood by giving c negative blood. SInce we don't have f antisera, we usually give c negative blood to patients with anti-f anyway.

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One of the "better" ones that I have come across (in a DAT 5+ patient) was a query anti-k, because the plasma reacted with all the panel cells, and there were no K+k- red cells in the panel.

It was a pan-reactive auto-antibody!!!!!!!!!!!

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Ouch! It is scary that there are people out there who don't know what they are doing. I don't know how to prevent it except vigilance and knowledge sharing on the part of those who do know. I've seen people just ignore reactions because they did not fit their preconceived idea. I did on one occasion refuse to have a second shift generalist in blood bank because he was not capable of interpreting antibody identification panels. He was a nice guy, but he was completely incapable as a blood banker.

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I know this is going off the subject, but I also know of one person that "missed" an Oh (fortunately known), because the reverse group didn't fit group O (so he ignored the reaction of the plasma with group O cells).

He did not get the opportunity to make this mistake twice!!!!!!!!!!!

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Ok, well I have to tell some of my stories now. Both of these were from clients when I was a Reference Lab Supervisor.

1. 1 Hospital sent us (within weeks of each other) 2 hemolytic transfusion reaction work-ups; 1 patient with anti-c and 1 with anti-E and anti-c. And they were hemolytic; you could not see where the cells stopped and the plasma started. The thing is, both patient had positive antibody screens pre-transfusion. And both patients had a panel performed. And on the panels, in both cases, the antibodies were strong (2+) and clear cut. So why the hemolytic reactions? They had a Policy that when they got an antibody, they always tried to prewarm it; if it went away, it "was nothing;" if it didn't, then they had to identify it and provide antigen negative blood!! And as scary as that Policy was, I don't think they even noticed the "beautiful; perfect" specificity on their panels! We should all have such nice panels to identify! After the 2nd reaction, I called their Medical Director and strongly suggested that they "cease and desist" with that Policy; and that furthermore, I felt that they should immediately send all positive Antibody Screens to our Reference Lab for work-ups in that I personally (if I were that Medical Director) would not sleep at night knowing they were doing work-ups. The Medical Director followed my instructions.

2. I used to put on seminars twice a year; all day; 6 speakers. The last hour I often had myself and the 2 managers of the other local reference labs in the area do an "Ask the Experts." Something that always came up (which I have very strong feelings about) is the issue of prewarming. We would even try to scare them, telling them the stories of Jka or Vel that were prewarmed away (but then more Techs. than I would like to think, also think V is Vel; so what can I say). It was not even a week later that we received a work-up from one of our Hospitals in which they had almost successfully prewarmed away an anti-Vel! Fortunately they failed; but too frequently, prewarming in the hands of many Blood Bankers is a huge risk!!

Brenda Hutson

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Brenda -

I have a couple techs who I think are a little to "pre-warm happy". Can you (or anyone out there) give me an explanation or references about why some clinically-significant antibodies "go away" when tested using the pre-warming technique? Is it just that an antibody that shows up 2+ with gel (or Peg, or whatever), could fail to show up with the pre-warm technique simply because of the lack of any enhancement media?

Donna

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I suspect the primary issue is one of technique. It is critical that each step be followed precisely; especially the temperature of the saline (and my guess is, this is where most of the problems lie). I think that if not followed strictly, just about anyone could prewarm away about anything! Certainly the stronger the antibody is, the more difficult it would be; but of course a weak antibody can be every bit as deadly as a strong one (especially if missed and an anamestic response is mounted). I have seen Jka antibodies prewarmed away; even by seemingly "competent" Techs. I am just very wary of prewarming unless performed by people with a lot of experience. But that is my bias....

Brenda

Brenda -

I have a couple techs who I think are a little to "pre-warm happy". Can you (or anyone out there) give me an explanation or references about why some clinically-significant antibodies "go away" when tested using the pre-warming technique? Is it just that an antibody that shows up 2+ with gel (or Peg, or whatever), could fail to show up with the pre-warm technique simply because of the lack of any enhancement media?

Donna

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It occurs to me that you might want to send a sample of the patient serum, if still available, to the manufacturer of the panels you were using to evaluate the unexplained reactivity on the cell labeled "f negative." f antigen status is often based on the presumptive Rh genotype based on the phenotype. Perhaps that cell is actually f positive. Adsorption-elution studies could probably resolve the question of the unexplained reactivity. For sure, that's beyond the scope of the average transfusion service, but it may interest the panel manufacturer.

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I suspect the primary issue is one of technique. It is critical that each step be followed precisely; especially the temperature of the saline (and my guess is, this is where most of the problems lie). I think that if not followed strictly, just about anyone could prewarm away about anything! Certainly the stronger the antibody is, the more difficult it would be; but of course a weak antibody can be every bit as deadly as a strong one (especially if missed and an anamestic response is mounted). I have seen Jka antibodies prewarmed away; even by seemingly "competent" Techs. I am just very wary of prewarming unless performed by people with a lot of experience. But that is my bias....

Brenda

I am right with you on this one, Brenda. Prewarming can be a very dangerous technique. I require at least a demonstration that there is a cold reactive antibody in the sample before I even allow it. Of course many samples have a naturally occuring cold antibody that has nothing to do with what is going on in the screen, but I have had techs who wanted to do a prewarm and the cold screen was completely negative.

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John Judd used to call it the "pre-fried" technique because so many people would use 40C saline instead of 37 etc. His study seemed to conclude that part of the reason pre-warming missed significant antibodies was the lack of additive. Combining that with the abuse of the technique it can be quite dangerous, especially if used to "get rid of" reactions. Its only proper use with modern reagents is in the presence of a really strong cold agglutinin and those are pretty rare. I agree that you must prove that there is a cold Ab present before pre-warming.

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What is "pre-warm technique" ?

It is an indirect antiglobulin technique where the plasma, and the red cells are brought to 37oC before mixing together. After mixing, they are then incubated at 37oC and then washed in saline that is at 37oC, and then then AHG is added. It can only really be done in tubes (although I have come across people who claim to have done something similar using column agglutination technology - goodness knows how!!!!!!!!!!!!!!!).

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It is an indirect antiglobulin technique where the plasma, and the red cells are brought to 37oC before mixing together. After mixing, they are then incubated at 37oC and then washed in saline that is at 37oC, and then then AHG is added. It can only really be done in tubes (although I have come across people who claim to have done something similar using column agglutination technology - goodness knows how!!!!!!!!!!!!!!!).

Thank you, Malcolm.

I can't believe this technique can loose some clinical significant antibodies, this make me shocked. Maybe it is because the temperature not 37oC but more than it, or because the body temperature not only 37oC, we must admit it some people such as my lab manager's body temperatue is lower than 37oC, she is 36oC.

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John Judd's study showed that it did miss some antibodies. It is a saline technique so would not pick up anything that is dependent on LISS, PEG or other additive. The warming to 37 should not cause a problem but people warm the saline to even higher temperatures sometimes which probably does a weak heat elution.

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It probably does Mabel, but if one looks at the original work performed by Nevin Hughes-Jones at Cambridge University on optimum reaction criteria, it probably has little effect.

I honestly don't know what is causing the problem, but it would appear to be a "green fingered" technique (a bit like the Chown capillary technique) that works for some, but not for others.

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So, Brenda, when you say the R1R2 people are the ones you would expect to form an anti f is it because of the position of the c and e?  I’m trying to wrap my head around anti f. We have a patient who our reference lab identified an anti f and the patient is R1R2. 

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4 hours ago, Paul said:

So, Brenda, when you say the R1R2 people are the ones you would expect to form an anti f is it because of the position of the c and e?  I’m trying to wrap my head around anti f. We have a patient who our reference lab identified an anti f and the patient is R1R2. 

Sorry to jump in here, but it is NOT the position of the antigens that allows the formation of anti-f, but the RHCE genes that have been inherited.  If the individual is truly an R1R2, they will have inherited one RHCE*Ce gene and one RHCE*cE gene.  In other words, the "c" gene and the "e" gene are in trans, whereas, if the individual is actually an Rzr (or RzRo), they will have inherited one RHCE*CE gene and one RHCE*ce gene.  In other words, the "c" gene and the "e" gene are in cis.

Therefore, if the genes are in trans, the individual can make an anti-f, but, if they are in cis, the individual cannot make an anti-f.

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Thank you for the explanation. Your explanation does help me understand it better. I hard a hard time finding in depth information on f. 

Edited by Paul

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