We just had a patient come in with a previously identified E, K, and cold auto. Now there is something else there we couldn't identify. The reference lab reported Cw, Di(a), V, and S.

I just don't believe it. Cw, Di(a), and V are extremely low incidence antigens. What is the statistical possibility that a single patient can be exposed to all 3 of these antigens with just a few transfusions?

I voiced my concern to the Reference Lab Manager, but they stuck by their report.

As with all Ab identification, it is a statistical probability that drives the report. If the patient exhibits the usual "3-pos,3-neg" reactivity and types negative for the antigen, we say we've identified something and infuse antigen-negative, AHG-compatible units (if significant) with good success. It doesn't always means the ID is correct ...

If patient already has more than one antibody, the patient could be a hyper-responder, who, with enough exposures, will form every antibody that their genotype will allow.

I have to agree with Larry... we have a patient like this, he has made multiple antibodies, including several low frequencies.

Linda F

Patients who produce antibodies to one low frequency antigen commonly produce antibodies to other low frequency antigens as well. Low frequency antibodies are very commonly found in conjunction with anti-E and anti-S (can't tell you why). In our reference lab, we have one patient with 27 low frequency antibodies so this report does not seem outside the realms of possibility.

David

It well documented and if you take a look at Issitt's Blue Bible "Applied Blood Group Serology"

you see numerous citations where certain serums contain loads of antibodies to low freqs--the Blo serum contained antibodies to Bpa, Gf, Jna, Moa, Or, Pta, Ria, Swa, Tra, Vga, Vw, Wra, BOW ans Skjelbred--a real hodge podge of goodies

These patients must have been transfused a bunch to accumulate exposures to that many low freqs! Or they have very bad luck.

Hey Mabel, Our 2 "disaster" patients are very exposed. One is a Beta-Thal patient and the other is a 54 yr old sickle patient. Our Beta-Thal just moved. She was 21 and has recvd products her whole life. Her % was 3 out of 10000 from random units. Obviously we did not start with "random units" each time but finding 4 for her every 3 weeks was a true challenge. Our sickler had a Fy5 on top of her normal and low-freaks. We have "mad scientists" theories that these people may be in states of hyper-sensitivity due to their conditions or drug regiments but it is a well known fact that we are just crazy.

I would like to respond since I am a senior tech at the IRL who did the ID on the patient in question. Of course, we follow the AABB IRL guidelines when identifying a specificity. The patient in question also has anti-E, -S, -K and -Fya in addition to the –Cw, -V and –Dia mentioned previously. This patient has made all of the commonly encountered allo antibodies that we would expect with his phenotype. He has a history of GI bleeding and has had multiple episodes at various local hospitals dating back to 2005. We often fill his requirements from our Ro phenotyped inventory due to his antibody history. As can be assumed, most of our Ro donors are either African American or Hispanic and therefore it is not unlikely that the patient has been exposed to the V and Dia antigens. Since the patient does not require C negative units, exposure to the Cw antigen is also not unexpected. As we test this patient in the future, we will likely identify other antibodies to low incidence antigens as these happen to be on selected cell panels. I would imagine that other reference lab staff would agree with me that we do not identify these specificities as a whim. Once identified, we are faced with having to decide how to handle them every time we get new requests for red cells. Julie

As a Reference Lab tech, I can tell you that we do not hang antibodies onto patients lightly, especially antibodies to low incidence antigens. We are usually the party who has to find compatible units for the patient and antisera for lows is either very expensive, unlicensed or non-existent. A hasty antibody ID would only make more work for the Reference Lab in the long run.

More important, like our hospital-based brethren, we take pride in the work we do. And we care about "our" patients, even though they are not directly under our care. So shortcuts and incompletely proven antibody IDs are totally unacceptable.

Dear Julie

Out of curiosity, do you know which antibody/ies this patient made first? And after how many transfusions?

Thanks

Gil, this might be one of those cases where knowing about transfusions at other facilities makes interpretation easier. It is really easy to skip getting history--and history isn't always easy to get or accurate--but not knowing can sometimes cause confusion, as in this case, or sometimes burn us because we thought the patient was not recently transfused. I will admit to being guilty sometimes of not pursuing history if the case seems clear--but someday it will get me.

Julie,

I don't know what the statistical incidence of Cw, Dia and V are in our Hispanic/Black population in S FL, but I thought each of these were about 1:1000. (I know that Dia is about 8% in Asian population, but in Hispanic, I have no clue). Wouldn't that make the odds of being exposed to all 3 low incidence antigens like 1 in a million? That is the sole reason I questioned the report.

I also worked on this patient. I had 3 Dia positive cells from 3 different panels, but none that were negative for S, E, Fya, or K, so I couldn't prove or rule it out. Same with Cw, just couldn't rule out.

Julie, I apologize for questioning your work on this patient. I think it's definately an interesting case. I saved the plasma from 5 tubes, to investigate more.

After all the phenotyping we paid for on this patient, they never transfused him. This patient has been hospital hopping in S FL, which is never a good idea when you have all these antibodies.

Gil