exlimey

Exactly. And very likely to cause in vitro hemolysis in appropriate test systems (not to mention in vivo hemolyis). I remember doing many 2-stage EDTA tests, using fresh complement and poly AHG. Good times. I think I may have met Dr. Cedergren when I was working at the BGRL in Oxford during the late 1980's.

I can't really explain your serological findings, but I agree with Malcolm's sentiment: "That stuff'll kill ya!" Anti-Vel is notoriously slippery and infamously dangerous. Without a more detailed look at your results, I see a few remote possibilities: 1. The anti-Vel may have an IgM component that doesn't like the Gel, but does like the PEG test 2. There's possibly something underlying the anti-Vel, hence the "extra" reactivity 3. The unit you crossmatched is not actually Vel-, but another member of the Vel variant club

While the use of EDTA plasma basically eliminates the chance of detecting hemolytic antibodies (as Malcolm says above), some laboratories still use serum. It's possible some hemolysis might been seen in visual check before taking the serum-RBC-PEG reactants to IAT. One may also recognize loss of RBC volume after the washing process, if some of the cells were destroyed during the incubation phase.

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 ??