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Posts posted by exlimey
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As Malcolm points out, washing is not really important for ABO grouping in the modern era of tube testing. The reagents are formulated to tolerate a degree of neutralization. I assume this is true also for the reagents used in gel cards. Washing is important when using the cells in any test using antiglobulin reagents (as LIMPER55 notes).
Perhaps more of a concern is that your in-house procedures should not contradict the reagent manufacturers' instructions. One could even argue that an SOP is not really required if you follow the package insert - that's your SOP!
Whichever approach you take, you should definitely be following your SOP. I can see and hear the regulatory folks cringing in their seats as they read your post.
- Malcolm Needs, Kandahlawi and galvania
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A blanket policy like the one gagpinks describes will result in a lot of clinically irrelevant testing (as Malcolm so elegantly stated). Having a policy is a good idea, but it must be applied with precision, on a case-by-case basis.
An eluate may be relevant if there's clinical or laboratory evidence of a transfusion reaction. I've heard of policies where a significant change in the strength of a post-transfusion DAT triggers preparation of an eluate. However, as Malcolm also points out, such eluates in persons with "warm-autos" are almost useless, unless one is prepared to perform adsorptions on the eluates to look for alloantibodies behind the auto.
- SMILLER, gagpinks and Malcolm Needs
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20 hours ago, Cliff said:
For non allo donors we only ask questions to ensure the donation is safe for the donor.
Agreed. One could also add questions related to the anticipated use in a research project - anticoagulant therapy, aspirin use, etc. That kind of information might be pertinent to the research lab. Wouldn't be a lot of use collecting platelets from a donor who has been taking Plavix, for example.
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1 hour ago, goodchild said:
If you read the manufacturer's instructions for Ortho Gel it says: "In some low ionic strength test systems, certain antibodies, such as anti-E and anti-K, have been reported to be nonreactive."
Good point. I know that the Gamma/Immucor PEG reagent available in the US does have low ionic properties. Don't know about other suppliers, but it's common for reagents like these to be very similar.
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PEG-only antibodies are well known, but it's common that they can also be detected in one of the other very sensitive methods (Gel or Solid Phase). The LISS method is less sensitive than PEG and it's not surprising that you can't detect it there.
It is possible that the PEG reagent contains a chemical that is critical to the reactivity of your patient's particular antibody. There are lots of documented examples of "chemical-X-dependent" antibodies. The absence of the specific chemical from the LISS test and the Gel system would render it nonreactive/undetectable.
Trying another manufacturer's PEG reagent (presumably with a different formulation) might clarify the situation.
- WisKnow, R1R2 and Malcolm Needs
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4 hours ago, Malcolm Needs said:
The Lutheran antibodies can be essentially IgM, a mixture of IgM and IgG or IgG (but IgG only is most unusual), and, of course, IgM antibodies would not be expected to pass through the placenta. However, even if there is an element of IgG Lutheran antibody in the maternal circulation, foetal Lutheran glycoprotein is expressed on placental tissue, and so these ectopic (for want of a better way of putting it) Lutheran antigens will largely adsorbed out the maternal Lutheran antibodies.
I agree completely. Hence why I wrote "partly due to their poor expression". And, don't forget, if antibodies to Lutheran system antigens are in part IgG, they are often they wrong subclass to readily cross the placenta (IgG2 and IgG4).
- gagpinks and Malcolm Needs
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On 9/17/2016 at 5:16 PM, Mabel Adams said:
Supposedly cord blood doesn't react with anti-CD38. I suppose if they have K pos cord cells they could have ruled out anti-K but you can't get them commercially anymore. Where does a reference lab get them? Sounds like someone has mixed up some information or has miscommunicated (and it's not you).
I agree - mixed-up information. If CD38 is only poorly expressed on cord cells, it would make sense that they would be less likely to react with the therapeutic anti-CD38 antibodies.
Many workers believe that antibodies to Lutheran system antigens (also carried by CD38) rarely cause HDFN partly due to their poor expression on cord cells. This seems to parallel one of the mixed concepts above - no antigens on cord cells, no reactivity. If this is true, then K+ cord cells could, perhaps, maybe used to exclude anti-K in Dara patients. Not quite sure how you'd put that in a report.
However, having access to a large number of cord cells and the ability to mine them on regular basis for K+ examples seems like a pie-in-the-sky situation. It might be possible in a large, competent Reference Laboratory that has a good working relationship with a large maternity hospital. Might be some ticklish Informed Consent issues, but.......at least its feasible.
As to typing the patient - monoclonal IgM anti-K reagents are available. This makes the DAT moot.
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A few points, but first, a disclaimer: I am not an expert in FDA or CLIA regulations.
I suspect that many labs are using some form of a "home-brew" reagents. The number of internal controls required by various regulatory agencies increases by the day. Add the large number of "competencies" necessary for all the staff and one has to use what is available.
Personally, I don't think viral testing should really be an issue (although it would be nice to know) - you're not preparing this stuff for distribution/sale to other facilities; the "treat all materials as potentially infectious" mentality and Universal Precautions approach should cover you.
The absence of an expiration date is probably better that assigning an arbitrary one (you have no stability data). In your application, you have a in-built control - it either works or it doesn't (I'm presuming you test the untreated [positive result] and the treated cells [negative result]?).
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On 9/10/2016 at 7:31 PM, Mabel Adams said:
Does anyone know how long the DTT treated cells are stable? Our reference lab makes them up as needed as I expect we will, but it would be interesting to know if you could store them for a few days or weeks. They might be able to freeze them as they do rare cells. I doubt they would last long due to lack of preservatives. As I recall, if we dilute 3% cells to 0.8% in the Ortho diluent 2 that lacks preservatives they are to be discarded after one day.
On the surface, "stability" of red cell products appears quite simple. However, there are a huge number of variables to consider, especially the age of the cells when put into use. Chemical- or enzyme-treatment of those cells adds another huge wildcard - it certainly voids the original expiration date assigned by a commercial supplier.
One approach may be to treat cells of a known/fixed age, suspend them in a commercially available red cell preservative, and then test the untreated (in the same preservative) and the treated for the presence/absence of a variety of antigens over the course of a few days or weeks. Ideally one would test all the "clinically relevant" antigens. Or, one could choose those antigens that are thought to be less stable over time. The best serological way to detect weakening of antigens would be to prepare serial dilutions of the test reagents and run titirations against the untreated and treated versions of the test cells.
It's a lot of work and all the commercial suppliers have done it for all of their current red cell products. However, I doubt that they will ever supply DTT-treated cells since the market is so small and potential profit very limited.
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Could be an (auto) anti-LW, not uncommon in older folks. DTT- or AET-treatment of the test cells might give some insight.
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Most of the common Rh antibodies have been reported as IgM. A "saline-reactive" anti-E is probably the most often seen. I've personally seen an anti-e that appeared to be IgM.
Way back when, in the dawn of time........there was serious concern over examples of IgM anti-D potentially causing ABO reverse typing discrepancies - hence why the commercial reverse calls are all Rh-.
- Malcolm Needs, gagpinks, NAN47 and 1 other
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On 7/23/2016 at 0:03 AM, WisKnow said:
Here is a weekend case: Patient's sample was A (forward) and backtyped as AB with provue. Tube testing was AB with forward and back typing, however it was only 1-2+ with anti-B. T
It's a bit unusual for the tube typing to be more "sensitive" than the automated (and I use that term loosely). May I presume that the anti-B used on the Provue and in the tube tests are formulated from different monoclonal cell lines?
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Mabel is quite correct - I also remember that there were a number of ticklish "administrative" issues.
A more technical note: Since the volume red cells from one cord are small, I suspect the the products that were distributed were POOLS of cord cells. That is the only way that the manufacturers could have enough volume to make a viable product. A pool would mean a mix of phenotypes and the product wouldn't be much for the application suggested by WisKnow.
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1 hour ago, Pony said:
Just to clarify a few misconceptions:
1. Once a package insert change has been approved and new stock is in, IT IS SOP-driven that all old versions are destroyed and not used in new packages. If you ever get 2 packages of the same product with different version inserts - report it immediately to the company. Major labeling booboo!
Pony,
I don't think anyone suggested that they get a shipment of reagents (with the same lot number) with varying inserts.
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3 hours ago, macarton said:
A few times we have gotten a new insert in the reagent, but the company still has the old one still on line. I'll contact them asking them to e-mail me one and correct on line.
A word of caution: The "old" insert may still be relevant to in-date reagents on your or others shelves.
But saying that, it doesn't excuse the absence of the new insert.
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23 hours ago, Brenda Hutson said:
So I guess I am not so much talking about them making changes but the Inserts don't reflect it. (because they are still sending out old inserts until they use them up....though that is not good either)....I am talking about Inserts that have a different Version Number/ Date so you know there are changes in there.....somewhere.....but you can spend a lot of time looking for a one word, insignificant change. As long as they are changing the Insert and sending out those new Inserts, it would be "so" helpful if they would (like Immucor) just indicate in "some way," what changes they made (i.e. underline it; highlight in gray; etc. etc.; don't really care what they do as long as they do something). That is good customer service!
Thanks
Brenda Hutson
I agree, Brenda. Immucor does a relatively good job of indicating changes. It can get a little ugly when the same "new" insert (with highlighted changes) is still being issued many years after the change. Perhaps Immucor buys a minimum number of inserts with highlighted changes and at some point transitions to the "clean" version ?
In the recent years, in the wake of mergers and consolidations, I've noted that the changes are often just name, logo, address or telephone numbers - of no real impact to the average user (unless you need to call Customer Service, of course).
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On 7/1/2016 at 4:53 PM, mollyredone said:
Immucor does that. They underline anything that has changed and use a closed triangle for anything deleted. I've attached a copy of one from 2010. What bugs me we get a new insert in 2016, and it was changed in 2013! Where has it been all this time??changes.pdf
The short answer: Money - throwing stuff out is expensive.
The long answer: To get a good price for printed materials (package inserts, labels, etc.), one must purchase tens of thousands of copies. If changes are required, but not especially critical, the regulating bodies (FDA) will allow manufacturers a fair amount of leeway to use up current stock. Throwing out anything has an associated cost and since the commercial manufacturers are in the for-profit arena, they will tend to shy away from such actions. I'm sure this contributed to Immucor's tardiness.
Another contributor to slow moving changes: In the US, any changes to a package insert (or label) must be approved by the FDA before that new document is distributed. This process can take 6 - 12 months depending upon the complexity of the changes and the number of times the document goes backwards and forwards between the two parties.
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13 hours ago, WisKnow said:
No, he did not receive IVIG. That was the first possiblity that we looked into. But there's one thing that we noticed. The washed A, B and AB donor cells were stronger with patient's eluate than with the unwashed. I already mentioned that eluate was negative with both washed and unwashed O donor cells, also negative with unwashed A and B cells. So we will try to wash the A1 and B reagents cells and see what we'll get. We have a feeling that the reagent cells express antigens weakly and by washing may uncover more antigen binding sites.
Reagent red cells certainly do not "express antigens weakly". There is no way a commercial entity would risk distributing a product that might give rise to customer complaints - the regulating bodies (the FDA in the USA) would be all over those issues. There may be some weakening of antigen strength over the life of commercial red cell products, but this weakening would probably only be noticed with a borderline, wishy-washy antibody - perhaps you have stumbled upon such a beast.
Commercial reverse cells (A1, A2, B, O) are washed extensively before preparation of the products. Additional washing will not "uncover more antigen sites". At most, washing (with saline) will remove the commercial red cell diluent/preservative and change the chemical environment of the test system. This change may indirectly enhance or suppress reactivity of some antibodies.
If you are using unwashed cells in ABO tests, remember that ABO substance will also be in the plasma/serum and may neutralize an antibody before it has a chance to bind to the red cells. In such a case, washing will definitely enhance reactivity.
- Yanxia, Malcolm Needs and WisKnow
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Red cells that contain HbSS (or HbSC) are more resistant to hemolysis in hypotonic environments than cells carrying "normal" hemglobin.
This makes it a useful technique to recover autologous cells from transfused sickle cell patients (providing the patients have some level of native RBC production). It is not useful for harvesting autologous cells from transfused patients who do not have HbSS.
A reference: A Rapid Method for Harvesting Autologous RBCs from Patients with Hemoglobin S Diesease. Brown D., Transfusion 1988; 28:21-3
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On 5/23/2016 at 11:17 AM, Sandy Jo said:
Quick! Does anyone have a form they are willing to share (or post in the Library) for method comparison of Blood Bank assays? I would like to include a minimum of 10 patient samples and correlate between Solid Phase (Echo) and tube testing for ABO/Rh and Antibody Screen.
Thanks so much!
Sandy
Sandy,
How do you deal with discordant results? There's a great difference in sensitivity of the assays you mentioned. Or do you bias the results beforehand by making sure your test samples perform in each system? Not a criticism, just wondering.
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Perception is important, but education can help smooth over the concerns. I think it's important to remember that the outside of the bag "lost it's shine" as soon as it left the shipping box and was used to collect blood. There is nothing sterile about a church hall, a high school gymnasium or any other of the myriad of places blood is collected. I wonder how hospitals reconcile the fact that "dirty" blood bags are transported into and used in their super-clean surgical suites ?
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39 minutes ago, Malcolm Needs said:
I see from where you are coming, but, when we used to test donors for DAT in the UK, it was done on the satellite tubes, where the blood from the arm was allowed to flow straight into EDTA tubes, and only a small percentage gave a positive DAT.
A valid point. It is not uncommon to find a spurious positive DAT in a sample collected in EDTA tube, especially in "older" tubes.
My point is that crossmatches use segments (pigtails) and the presence of the sugary-goodness in the collection systems can also cause positive DATs.
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I agree with Malcolm's comments and would add that I suspect that many positive DATs in donors occur after collection of the blood, i.e., the donor is not actually DAT+ in vivo, but somehow the red cells pick up globulins during exposure to the chemicals and environment of the collection system.
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sbazel - bad idea to use the earliest expiration date of the components of your cocktail. Neither apply to your working reagent. Certainly the anti-D has been grossly modified from its original. To assign a genuine expiration date to your cocktail, you would be obliged to perform a formal stability protocol.
Preparing red cell suspension for grouping
in Transfusion Services
Posted
I'd like to be a fly-on-the-wall when you have that conversation with an Inspector......just kidding. I suspect many folks are doing just as you describe and for the same reason.