exlimey

1. Personally, I wouldn't do ANYTHING different/extra than the manufacturer recommends. You may inadvertently "modify" the process and find yourself in a corner that requires validation of your local modification. Yikes ! 2. Typical eluate volumes are quite small - often too small to be measured with a pH probe. So I suspect, correct me if I'm off-base, that the pH has been checked using pH paper. If so, eyeballing the color of the pH paper is no better than eyeballing the color of the eluate. And, as AMcCord suggests, while the blue color may vary, the differences in pH values of the different blues is very small. The manufacturer (Gamma/Immucor) has put a lot of effort into making the kit idiot-proof.

Interpretation #3 should only be considered if a polyspecific antiglobulin reagent was used, i.e., a "complement coat" will only be detected if the antiglobulin reagent used contains an anti-complement component. Even if that is the case, Interpretations #1 and #2 are far more likely.

What does the Blood Center do with the K+ units ? Throw them out, or only give them to K+ patients ?

This is a very interesting thread, partly ethics, partly practical use of resources, and a large dose of "what if". In the legal sense, the concept of "Prior Restraint" comes into play - doing something to prevent a possible event regardless of probability. So.....a not-so-unrealistic scenario: The hospital has a patient with anti-K and is required to screen/type a number of units to fill a transfusion order. During the process some donors/donations are identified as K+. What should the facility do with those, knowing full well that they may stimulate an immune response in recipients ? And.....discuss.....

Unless you have the right contacts......

They may indeed "cause very mild delayed transfusion reactions", but to a multi-transfused (Sickle Cell Disease, SCD) patient, with often a multitude of other alloantibodies, what would be a typically mild reaction in a "normal" patient can be serious, even fatal in SCD patients, especially if it induces a hyperhemolysis event. SCD patients understandably have very fragile immune systems. It doesn't take much to upset the apple cart. They sure do, especially since many laboratories routinely use the super-sensitive assays like PEG-IAT or CAT (gel/bead technology) for crossmatches.

Most examples of anti-K are IgG, and therefore need an antiglobulin test to detect them. While enzyme-treatment of cells may or may not enhance reactivity of anti-K, it rarely turns an indirect agglutinin into a direct agglutinin. It does happen, but I've only seen it with Rh specificities where antigen density supports the process. I presume that the "neutral cards" do not contain anti-IgG and therefore your findings are as expected/typical for most examples of anti-K.

I am Bg(a+) and my expression is usually quite strong; it got super strong after a bout of Infectious Mononucleosis. I have seen my own cells react with examples of anti-Bga when the cells are fresh and then reactivity dwindle to nothing as cells from the very same collection tube age.

Definitely nonsense. In my experience, antibodies to Bg antigens ONLY react with the freshest of cells, and only with individuals with unusually strong expression of the antigens, e.g., Bg(a+s). Even when the odds are stacked in your favor - fresh cells from an individual with a strong expression, you're only likely to get barely macroscopic results. It can be very frustrating to chase down one of these to identify it.

I concur with the autoantibody conclusion. However, unless you've neglected to tell the forum important details about this case, this work-up should have stopped at a negative antibody screen (in cards). I'm more concerned about why are you doing lots of extra work - especially an enzyme panel. And, why, oh, why are you using a "primitive", "insensitive" tube test when the super-sensitive card tests are negative /compatible? If this is a "normal" work-up, I believe your testing algorithm needs attention.

Do you plan to grade/record your antiglobulin control cell reactions ? If "YES", then you will need to define an acceptable range. Most workers simply use a check mark to signify satisfactory performance (hence "Check Cells"). In the absence of specific instructions and/or ranges from the antiglobulin control cell manufacturers, I favor the position suggested above by AuntiS: Macroscopic agglutination.

What's wrong Malcolm ? You don't like the idea of using a Coombs Test to find Kell- blood ??

The avidity/reactivity of freshly-prepared antiglobulin control cells may be sufficiently high that the obligatory mixed-field result is not seen. The agglutination matrix of the sensitized cells often incorporates the un-sensitized test cells - a clear background is very possible. Some workers believe that 2+ is too strong and that 1+ with antiglobulin control cells is the prefect result and allows detection of a decrease in sensitivity of the assay.

That's interesting. The last time I purchased spirit thermometers, we were unable to certify them (we didn't pony-up the extra $$$ for NIST-traceable versions). We had serious linearity issues between the ice-point and the working temperature. The mercury replacements had perfect linearity, but I understand the concern regarding mercury.

Do you use liquid-in-glass thermometers ? If so, spirit (alcohol) or mercury ?

Interesting. My perspective is from the USA. I assume then that the donors with detectable antibodies are permanently deferred ? That must put a hurt on the supply of Rh-.

Another remote possibility: Passive anti-D from one of the transfused units ? Most facilities are shy about transfusing red cells from donors with antibodies, but some of the savvy hospitals will get "favorable pricing" on Rh- units with anti-D. Since the Rh- unit (with anti-D) is typically going to an Rh- patient, the presence of the antibody is not usually a clinical problem, but may turn up as a laboratory anomaly. The amount of residual plasma in today's red cell products is very low, but a strong anti-D might show up post-transfusion and would probably only be seen be temporarily. You would have to look the timing of the transfusions and collection/detection of the anti-D-containing specimens. If you see a pattern, your blood supplier may be able to determine if any of the transfused units were from donors with anti-D.

Excellent points. The diagnosis, i.e., the reason for transfusion, might also give a clue. I also thought about RH-IG, but I can't think of a traditional use for that product in an elderly patient.

It might be a transient autoanti-LW, only reacting with D+ cells. Genuine examples of anti-D are usually more persistent than the situation you outline, but never say never. An elderly person's immune system may work in unpredictable ways. On a related tangent....if it is a "real" anti-D, I would wonder about the source of immunization - I'm assuming D- RBCs were transfused. You do not mention platelet transfusions.

Nice !!! Old School.

If by "odd antigen" you mean a low incidence/frequency antigen on that specific A1 cell/donor, it should be easy to resolve using another A1 cell (or set of Reverse Cells) - the forward and reverse would compliment each other. However, if everyone is having problems with this patient, it's unlikely to be the reverse cell(s). Is the GI bleed due to ulcers ? H. pylori, perhaps. I think I read that some folks with H. pylori make cold autoantibodies.

So the A1 cells are reactive, but the O cells are nonreactive. Interesting. I would have guessed autoanti-H, but that doesn't fit. Have you tested A2 cells ? Might be a weird compound antibody like anti-HI - needs the presence of both antigens to react well. Have you looked at something simpler, like anti-M, for instance ? The DAT results suggest IgM/complement binding, but as you imply, further testing is required.

I agree - sounds like a cold auto, probably IgM. The IgG-gel cards are not exactly good at detecting IgM antibodies, Perhaps that's the reason for the nonreactive screens ? What do O cells do in your standard version of the "reverse"?

Where are the lights ?

Along the same lines......the basis of my personal safety approach: "If it's wet, and NOT yours, don't touch it."