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exlimey

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Everything posted by exlimey

  1. My two cents: One CALENDAR month........If you open something on the 15th, it expires on the 15th of the next month, regardless of how many days are in the current month. But...... you have to be careful to not open something on the 29th, 30th or 31st of January..., or the 31st if the next month has 30 days....
  2. I'm sure there are lots of variations between both Complement content of sera and the number "binding sites" on red cells. I suspect others on this site can provide references. This is assuming you are using the same antiglobulin reagent each time: To even out the variations, I suggest you use a pool of Complement sources (3 - 5). You may also consider using a similar pool of red cells. This may help lot-to-lot consistency. Ideally, in a perfectly-controlled world, one should use the same Complement source(s)and red cell source(s) each time you prepare a batch.
  3. Interesting. I like the "no one else is having a problem" line - the implication being that the problem is a result of something done by the end user. Random contamination (darkening) seems to be the bane of red cell manufacturers. Often, the randomness is exactly as you describe: one vial bad, another of the same batch is fine. It's very difficult to pin down a cause - could be their storage solution, could be inadequate sterilization of the containers/droppers, could be shipping, etc. I doubt there will be any resolution. I would send them pictures and ask for replacements.
  4. Is the supplier of the affected panels the same as your source for Red Cell Storage Solution (Alsevers)?
  5. An EXCELLENT question Darren ! I look forward to some interesting debate.
  6. I agree with Malcolm - the IgG/IgM nature of the antibody is not relevant, and I would avoid tests with enzyme-treated cells in patients with confirmed WAIHA, especially after adsorption procedures. I know that some workers also avoid PEG when testing adsorbed serum in these cases, opting instead for LISS or even saline antiglobulin tests on the adsorbed serum.
  7. Short (facetious) answer: $$$$$$$$$ Long answer - my opinion - Facilities required or choose to follow AABB Standards (and therefore get an inspection) are required to pay for/buy said standards. At the very least, they are "institutional members" that pay an annual membership fee. The AABB Standards are very different from the Technical Manual (in which the universal, public domain procedures reside). I may be wrong, but I think the standards get some kind of tacit approval by the FDA, whereas the TM gets peer-review. Of course, both documents/books are available to anyone for a fee......
  8. Thank you, Johnv. I know the science.
  9. Isn't it fascinating that we're "allowed" to deliberately use a less-sensitive assay when "we" feel it appropriate? Offhand, I can't think of anything similar in other path disciplines. Anyone ? Anyone ? And..... go........
  10. My interpretation: Users of POLYSPECIFIC antiglobulin reagents are obliged to verify performance each day of use, i.e., QC should involve use of IgG-coated cells AND Complement-coated cells. This gives the user confidence that the reagent is performing as expected. During routine testing, addition of IgG-coated cells to negative tests is sufficient to verify that the IAT was performed correctly - correct/effective washing, the antiglobulin reagent was added and is reactive, etc. If it were a requirement to add IgG-coated cells and complement-coated cells to every negative IAT using polyspecific antiglobulin, it would be necessary to run everything in duplicate - one set would get IgG-coated cells and the other set would get complement-coated cells. I don't think that is the case.
  11. PEG-IAT is arguably the most sensitive tube test currently in widespread use. For this reason you're more likely to see concurrence with your Echo/Neo results if you use PEG for supplementary testing, i.e., the sensitivity of the two assays are perhaps the closest (LISS being less-sensitive). However, there's still a chance that the Echo/Neo will detect something that is not detected in PEG (or LISS). I wonder what Immucor would say if you decided to use another manufacturer's PEG reagent ?
  12. I think the term "Chav" has recently become popular. Even more recently, calling someone "a right old Neymar" is not very flattering. As the Irish writer George Bernard Shaw once said: "England and America are two countries divided by a common language."
  13. Wow. Thank you for that information. That certainly could influence the concern some of the medics demonstrate. Is the surgical room also chilled ?
  14. That is exactly the theoretical risk that concerns the medical staff, but in my non-medical, laboratory-based opinion, the risk is extremely low. Extreme testing protocols (below 30 C) for cold-agglutinins are rarely informative, often having very specious clinical relevance. Does anyone really know what the results mean ? How high must a titration be to be significant ? If you look hard enough, you can find cold-reactive autoantibodies in most people, hence why routine testing protocols now deliberately avoid test phases below 37 C. Modern, super-sensitive test systems (PEG-IAT, CAT) don't even allow tests below 37 C and openly admit that IgM antibodies may not be detected (typically the form that "colds" take). Even with these "deficiencies" they still are licensed/approved for antibody detection and ID. If a patient is in such a dire situation that they're undergoing radical surgery, with the selective use of hypothermia and/or by-pass procedures, the least of their worries is a cold agglutinin. The easy fix to the transfusion of "cold blood" is a blood warmer, but obviously this would be contraindicated during hypothermic processes.
  15. Perhaps I'm a little naive, but I find some of the "old time" logic somewhat illogical. I appreciate that a unit of red cells being transfused would potentially be "cold" - 1 - 6 C at the start of infusion, i.e., might cause a cold-agglutinin issue, but almost immediately, the infused portion would equilibrate to the temperature of the circulating blood. Additionally, the unit itself would start to warm-up to room temperature. Certainly additional problems could arise from "by-pass" procedures, but are the devices\pumps "cold" - 1 - 6 C ?? I suspect they operate at room temperature, nowhere close to refrigerator temperatures. After all that rambling, I meant to say that I don't why anyone would test "cold autoantibodies" at temperatures below that of typical (surgical) rooms. However, I'm sure there is a a whole library of circumstantial, anecdotal evidence supporting such extreme testing protocols.
  16. Does the MTS gel card you typically use contain polyspecific antiglobulin reagent (anti-IgG + anti-complement) or does it just contain anti-IgG ? I think most users are using anti-IgG cards, and if that is the case, they're already dealing with the "Is it possible to miss a complement binding IgM antibody early on by using IgG only." issue.
  17. RESt = Rabbit Erythrocyte Stroma - basically stabilized red cell membranes from rabbits. There is absolute no DTT in RESt.
  18. I read on the Internet that if a person sinks in water and drowns, they're proven to be a witch........
  19. I suspect that routine use of enzyme-treated cells (in IAT) by "Non-reference Laboratory Staff" would cause more confusion than it would solve. Even the largest, most proficient hospital laboratory doesn't have high caliber serologists available on all shifts. I would suggest that tests with enzyme-treated cells be restricted to more difficult serological pictures, e.g., post-transfusion hemolysis without obvious cause (read "anti-Jka or anti-Jkb"), or for investigation of antibodies to high-incidence antigens. I also suspect that many of the "enzyme-only" specificities have a major IgM component - notoriously difficult to detect by CAT (gel). Just my two cents/pennies.☺
  20. Polyagglutination (one L) is a phenomenon demonstrated by some red cells in the presence of most normal human sera. It has little to do with a positive DAT. Perhaps you mean "spontaneous" or "non-specific" agglutination ?
  21. You bring up some interesting points and I agree with your position. Certainly "the literature" regarding the clinical importance of titration results is confusing. Most of the original work was done on anti-D, using an unorthodox test protocol (I believe the titrant was a high concentration of BSA), but there did seem to be some correlation between titration strength and clinical impact. Workers attempted to shoe-horn other specificities into the same program, with mixed success. Now, today, as you point out, the gel test is becoming a routine way to measure antibody strength. I don't think anyone honestly knows what the titration end-points mean, since the modern results are difficult to interpret/compare to the older literature. Time will tell. I think people have been caught in a little trap with regard to the controls needed for titrations. It is very unusual to have two sequential samples in a clinical assay, even rarer that one of said samples has been stored (frozen). Consider a simple CBC.....many patients with extended hospital stays have multiple tests performed. Their last samples are not run in parallel with the current sample, yet the results are considered valid because the instrument's controls performed as expected - this is the equivalent of using material with a known potency as a control for patient sample testing. The art is in selecting your control.
  22. Your results suggest to me that your QC reagent is deteriorating, maybe, perhaps, subjectively speaking, of course.☺ I am well aware that manufacturers test every cell for every antigen and that the results must meet a certain threshold. However, as Malcolm suggests, "decent strength" can be a very elusive target. One direct test with undiluted antisera (or a strategically-diluted sample) does not always give an honest indication of antigen strength.
  23. Yeah, that's one of the many fuzzy statements found in package inserts. I suspect that it means they perform a test to detect antigens and the reaction has to meet a certain grade. I doubt that they test the strength of antigens by titration or by another other more exotic means (FACS).
  24. (as there is no such gene as RHd, there cannot be a heterozygous form - exlimey!) - I stand corrected ! Thank you. Lastly, one would hope that, if the panel you are using is a commercial panel, they would have done something (perhaps a fluorescence-labelled anti-D and a FACS) to ensure that no red cells are chosen with a particularly low number D antigens expressed. - Not a chance of that happening.☺ The exons involved in the RHD gene leading to Partial D Category IV, are 2, 3 and 7 (exlimey), but even these express around 9, 000 D antigens. I was on the right track.
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