exlimey
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Posts posted by exlimey
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On 9/15/2021 at 8:08 AM, AuntiS said:
Sorry - just saw this reply now.
Canadian Blood Services tests all donor units for K. If K negative, the donor end label has K- on it. If K positive, the end label doesn't have any K antigen testing information listed - the K+ status is only embedded in the donor unit phenotype barcode.
All donor units are treated the same - so the K+ units are available, as all other units are, but it is easy to select a K- unit for females of childbearing potential and who are on a drug like daratumumab.
sandra
Thanks, Sandra. As I'm sure you knew, I am aware of the answer - no way, no how are blood suppliers going to "discard" ~10% of their product. But I think it's important to consider the consequences of some of the now routine testing algorithms. No testing mean results are unknown, but once one has information, one may be required to take action. Many transfusion protocols for chronic users involve Rh (C/E) and K matching - there's another batch of donors whose (partial) phenotype is known and considered to be quite immunogenic. It goes on.
I do find it interesting that your system "hides" the K+ status, but openly prints the K- attribute on the label.
Another thought: If the K type of all of the patients were known, they could get the K+ units. The antigen frequencies should match up.
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On 9/10/2021 at 3:09 PM, applejw said:
I suggest to my techs during training that it may be prudent to test the last wash before preparing the eluate - especially when additional red cells are not available. I'm sorry to report that I have seen several elutions where the last wash never became negative..... usually with cord cells where the mom had a VERY strong antibody - even changing tubes with every wash. I'm sure that if I had had the patience and persistence, it might have become negative but I gave up at 10 washes.
At that point, you could probably test the Last Wash for specificity !!
You'd probably get the results you need.
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I have always run the eluate and last wash in parallel, but the question did make me think.
I appreciate the attempt to reduce (potentially unnecessary) work, but don't like the idea of doing two-stage testing (eluate first and then Last Wash, or the other way around). If this happens, you've lost any efficiency (and time) you believed you gained by not testing the eluate and Last Wash in parallel. However, the cautious approach to a low volume (rare) specimen may have some merit - checking the Last Wash first adds confidence that any eluate prepared from the washed cells will be more likely to be valid.
The two-stage testing concept has crept into the laboratory over the last couple of decades and is completely valid for follow-up or reflex testing. But.....one of my peeves: Reagents that suggest "Immediate spin, incubate negatives". If you're running a negative control anyway and/or most of your tests will be negative (DATs with anti-Complement reagents), you'll almost always be incubating, so why bother with the Immediate Spin ?
Bottom line: Do what the eluate kit manufacturer says (unless you've validated otherwise).
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3 hours ago, David Saikin said:
(maybe it's ok because the "new" method is read microscopically vs macro read for the classic method).
Hah ! Excellent point, David. I wonder how much emphasis should be put on those "microscopic" reactions, especially when the endpoint a titration is most often defined as the "last MACROscopic (or 1+) reaction"? How do the Powers-That-Be justify that little nugget ?
Can you imagine resulting-out a "change in titer" based on a microscopic reaction ? Talk about piling-on to the already acknowledged confusion level.
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An excellent discussion point. I think many others have similar questions and concerns. The have been several other threads on this forum with similar subject matter.
As an Old Fart, I feel obliged to spout some (un-referenced) history. Most of the original work on clinical significance of antibodies in pregnancies was done in the absence of potentiators and definitely before the use of (semi)automated test systems. I think it was a "saline-IAT" using 22% albumin (BSA) as a diluent. Most of those antibodies were anti-D, for obvious reasons. There's not much out there in the literature in terms of controlled or organized studies regarding other specificities. There are a fair number of one-of-a-kind case studies, but most of the stuff is retrospective analysis of data. Basically, other than anti-D, nobody really knows what an antibody titer means, but as Ensis01 suggests, detecting a change in titer (increase) may be more important.
In an era when basic tube shaking is going away, it only makes sense (we have no other option) to convert to the new techniques and equipment, but I suspect that it has the potential to further confuse an issue which already has enough confusion to (dis)satisfy everyone. I don't envy anyone handling this hairball.
As a last thought...the high-powered potentiators (and techniques) used today don't reflect what's going on in vivo. Arguably, if one ignored the 22% BSA diluent, the saline-IAT is a better mimic of the in vivo scenario.
- Ensis01, Marilyn Plett, AMcCord and 5 others
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I am not aware of any LICENSED anti-Cob available in the USA. The American Red Cross system uses an unlicensed version for most of its Cob phenotyping requests. I believe Cob can be determined by the HEA BeadChip process (molecular typing). If you have a patient that needs Co(b-) red cells, I think those are your two options: PHENOtyping with an unlicensed reagent or units predicted to be Co(b-) by GENOtyping.
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My personal favorite Ch/Rg confirmatory test: Strong reactions with C4d-coated cells. Old school, but really cool to see.
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8 hours ago, lalamb said:
Believe this is in the new AABB standards.
If indeed two samples are mandated by standards, AABB or otherwise (I'm not doubting your information, lalamb), it would seem that from some of the responses here, many labs are going to have to re-tool their processes, including building such practices into their computer systems.
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16 hours ago, Malcolm Needs said:
And if the blood in the tube was taken from the wrong patient?
Ahhh.....the unanswerable question. My personal favorite: Even if the first and second tubes were collected from different patients, there's still a good chance they'll still match ABO group (~40% group O, ~40% group A, etc.). If one were a gambler, those would be good odds.
But, that being said, I still think two tubes are better than one.
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On 4/30/2021 at 2:40 PM, JeanB said:
We used to use infrared thermometers as well, but I believe that using temperature indicators such as Safe T Vue, HemoTempII etc is going to be more accurate.
Forgive my ignorance, but are the above stuck to the outside of the bag, and therefore measuring/indicating the surface temperature of the blood product ?
The "storage vs transport" hairball will be debated well after we're all dust.
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2 hours ago, JeanB said:
I was under the impression that infrared thermometers measure SURFACE temperature and not core? Are we allowed to use this?
How do you suggest measuring the "core" temperature without compromising the bag ?
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This is the best thread, EVER !!!! Keep it rolling, please.
- mrmic, Malcolm Needs, John C. Staley and 1 other
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I was originally trained using an "inverted microscope" - that was a thing of beauty. The light source was above, the relatively low-powered lens below. The cells stayed in the tube and the tube could be rotated to get movement and/or a suitable thickness of liquid in which to see the cells. It was great and very easy to use (even though it had a large footprint), but as others have commented, if one looked long enough, one could always find "friendly cells".
I'm not a fan of microscopic reading and I dissuade others from doing it. As I've said in the past, high level tools and techniques should only be employed by those who understand the limitations and consequences.
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On 2/19/2021 at 4:09 PM, diplomatic_scarf said:
I disagree. Most gel cards and Anti-D reagents won't detect DVI for patients. Fortunately I can find numerous suitable quotes, because it's true.
https://labs-inc.org/pdf/361_3.pdf
Apologies. I was discussing reagents used in tubes, not gel cards.
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On 2/17/2021 at 3:43 PM, diplomatic_scarf said:
"Modern anti-D reagents, while they are very good at detecting weaker forms of the D antigen, are specifically designed to NOT detect the most common form of partial D in Caucasians (DVI, or “D six”), so most Caucasian partial D patients will test as D-negative." -BloodBank Guy
https://www.bbguy.org/education/glossary/glp04/
I disagree. It is in the FDA's manufacturing requirements that DVI be detected. Unfortunately, I couldn't find a suitable CFR quote, but several of the Directions for Use I looked at from different manufacturers indicate that they detect DVI.
However, I agree that strategic differential use of reagents such as these on patients vs donors can certainly help the transfusionist and/or determine the necessity for Rh Immune globulin.
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14 hours ago, diplomatic_scarf said:
I think most modern Anti-D reagents won't detect DVI and these patients will test as D-negative. This is probably the answer. Anyways, this is the answer he gave his students. To me, the answer looks as vague as the question. Not "straight forward" at all.
IMG_2756.heic 2.45 MB · 4 downloads
Anti-D reagents are specifically formulated to detect DVI - that is REQUIRED by the FDA in the USA. It was also true of the human sera-based reagents I manufactured in the UK during the 1980s.
There was a period when anti-D reagents were approved for donors or patients. The reagents used for donors were required to detect DVI, arguably the "weakest" expression of the D antigen of the known D-variant and typically that meant an antiglobulin phase was required. Those reagents formulated for patients often were not designed to detect DVI (had no IAT) and subscribed to the "it's better to treat them as D-" philosophy.
Today's reagents are typically qualified/licensed for patients and donors, i.e., they are formulated with the same performance characteristics. Even so, all are a blend of monoclonals (IgM/IgG) since not one single clone can detect all of the "normal variants" (a great oxymoron).
Apologies for some of the antiquated terminology.
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2 hours ago, John C. Staley said:
Thankfully I'm R1R2!!!!
59 minutes ago, David Saikin said:Me too John
See....you've already got the makings of a club. You can celebrate your CEce heterozygosity together.
- John C. Staley and David Saikin
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10 minutes ago, Malcolm Needs said:
But don't forget that those of us who are DCe/DCe are ALSO f Negative!
Good point, but we're very unlikely to make the antibody.
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1 hour ago, John C. Staley said:
Thankfully I'm R1R2!!!!
Sorry, John. You'll have to start your own club. Perhaps "f-negatives Rule", or something like that.
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18 hours ago, Malcolm Needs said:
I, too, am DCe/DCe (R1R1). This is getting spooky! Maybe you are on to something exlimey, and should write it up for Vox Sanguinis, Transfusion and/or Transfusion Medicine, or maybe even Nature!
An interesting idea, but I'm not sure I want my psychological dirty laundry hung out for the world to see.
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1 hour ago, Malcolm Needs said:
Ah, but don't forget that, not only did I work in a Reference Laboratory, but am also a self-confessed pedant, and so, if a patient was both c Negative and E Negative, and had an anti-c, we would go to the ends of the Earth to prove the presence or absence of an anti-E, as a matter of pride!
I confess: I'm much the same way in the OCD sense. I'm also DCeDCe (R1R1), so perhaps this issue hits a little too close to the sensitive area.
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23 hours ago, John C. Staley said:
Couple of more strange questions, how sure are you that it is anti-Jka? If you are sure, why were you doing a ficin panel?
Can't wait to see what Malcolm has to say.
An EXCELLENT question, John, but as Malcolm suggests, is appears that there is still a large dose of "we always do that" in many laboratories.
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Short answer: Yes
How was the anti-Jka detected initially, i.e., what technique ? Assuming it was an antiglobulin test, but was it Gel, Solid Phase, LISS, PEG ?
Yes, the panel cells are now ficin-treated and antibodies to Jka should be enhanced, but the test conditions that were used in the original assay may not exist when ficin-treated cells are used - one may need to add LISS or PEG, one may need to test by Gel or Solid Phase.
Newly detected anti-D
in Transfusion Services
Posted
I'm in line with the above answers. A current diagnosis would be useful, especially to give us an idea if the aforementioned blood products (platelets, plasma) may be in play. There has to be some kind of more recent stimulus.