MTS-Gel Back-Up methods

[Seveets]

What are people's next step when Gel manual panels don't point you to an antibody? Send out, tube testing, something else?

We had mysterious results in both Panel A and B. We were able to rule out all major antibodies. The techs then went on to perform tube testing which were completely negative. A fully compatible unit was transfused.

I had my suspicions and repeated with a newer sample and found anti-Jka.

I don't feel comfortable that we went from a sensitive method (gel) to a less sensitive tube test method with no real reasoning other than to try and get rid of the positive results.

What are other people doing after strange gel results?

[jhaig]

If we don't get an ID in gel, we usually will send it out. While the specimen is being worked up by the reference lab, I will use my back-up panel to see if there are any specific cells to do rule-outs on. We just don't have the time or the staffing to do elaborate work-ups involving anything more than a repeat panel or an eluate.

[OPUS104]

Hey Christopher, We are a small ref. lab (only serve 28 hospitals) and have seen a VERY BIG increase in non-specific reactivity. (Gel and tube) We do not like to drop to tube testing unless the Gel is a pan. and/or other results point to a possible interference to justify our drop in sensitivity. In general, we see a reduction in reactivity of a factor of 2 between LISS and Gel. ie 2+Gel = neg. in tube. Of course you always have exceptions. I spoke with a much larger ref. a couple of days ago to see if they were experiencing a similar increase in non-ridentified reactivity. They have also seen a large increase and only use Gel as a back-up,,,, never their primary. Almost all of our larger hospitals that do their own Ab IDs have contacted us with similar concerns. Several of these that we have forwarded to large ref. labs have comeback as "HTLA" groups. I fear that the prevailing transfusion policies (ie trigger point transfusions) are going to increase the current problem.

[bbbirder]

We are seeing more non-specific reactions with gel lately it seems. If we get an inconclusive weak gel panel, we will test in tube (either with Peg or LISS). If negative, we usually just consider it negative, but do a full XM.

I guess I don't get too concerned if we miss a very low reactive antibody, I don't think it is likely to harm the patient. Remember when we used albumin as an enhancement?

Linda F

[Mabel Adams]

After making sure that all the antibodies for which commercial antisera is readily available have been ruled out (with a double dose cell if at all possible), repeating the gel tests with longer incubation and doing a gel xm, we transfuse. Occasionally I drop back to LISS when I am convinced I am dealing with a weak warm auto or HTLA-like antibody. I work really hard to rule out Kidd system antibodies because weak ones often won't react with one cell that they should but the only cells reacting are pos for the Ag and the patient is neg. I don't worry so much about non-Kidds. I will admit, if even Kidds are that weak, they still probably won't do that much damage. Kidd has such a reputation, I'm careful, but I have never seen it do its delayed TRX thing.

[geekay]

Hi there,

I fully agree with the opinion that the "gel technique" do give "false positives" , in the testing, may it be grouping, or x-matching, or antibody detection.....

In such a scenario, the golden rule is to return to the oldest and the most reliable technique of "manual" technique...

best wishes...

[galvania]

For Mabel -If you think you might have a Kidd but aren't really getting the 'right' results, you can try doing an enzyme coombs. You use enzyme-treated cells on Coombs cards. I would never recommend this as a routine because you will get lots on unspecific reactions, but a weak Kidd has a good chance of coming up like this

For Engeekay - if you're getting all these false positives, (and they really are FALSE positives) then there's something wrong somewhere.........

[RWOOD57]

We use panel C, it has the untreated and the ficin treated panels, The untreated panel is almost identical for to panel A. This has help us many times on weak antibodies that are enhanced. Ask your ortho rep for a sample. It has prevented us from sending many specimens to the reference lab.

Good Luck

[dstoever]

we had a very small weak reacton on the Provue on one screen cell, it was barely visible to the eye, upon repeat it became a little stronger, so we sent it out for Ab-workup. It was identified as a Kell. That would never have shown up by the tube method.

[Mabel Adams]

One of our frustrations is that our reference lab still uses tube so it would do no good to send out weak gel reactions as they would seldom find anything.

[AMcCord]

If it doesn't look like a warm auto, I like to go with a tube/PEG panel after the gel to rule out the major alloantibodies. If I suspect a Jk, I take a close look at my homozygous cells and sometimes run a panel of enzyme treated cells in tube. I also watch closely for E and K, since gel is known to miss those on occasion. I read the tubes with a scope when I'm working with weak reactions (yes, I know, hopelessly old-fashioned!). I also pay attention to those little guys lurking on the sides of the panel sheets or listed in the additional typing sections - some of my confounding reactions have turned out to be Coltons or a Diego or other weird things. I've seen these teamed up with a more common antibody and sometimes solo.

If it looks like a warm, but a weak one, I might still do a PEG panel. I have picked up a few weak alloantibodies rising above the 'noise' from the auto. Drop back to LISS if the PEG revs up the auto too much. AND don't overlook the possibility that you are looking at a cold antibody that is reacting very weakly outside of its happy zone. I've been called in to work on weak, nebulous reactions that have turned out to be Le(a) or M antibodies. We tend not to think about those with gel but they can show up. If it looks like it might be one of the cold antibodies, try setting up a quick screen IS and/or a 20' RT incubation with serum to point you in the right direction.

When I've satisfied myself that I've ruled out the major alloantibodies, I do an AHG crossmatch and transfuse the unit that is compatible (and antigen neg for anything else I've ID'd). I report an antibody of undetermined specificity. If I were closer to my reference lab I might punt sooner and let them do more of the work.

[Seveets]

Thank you AMcCord your steps are exactly what our new procedures are.

[Liz0316]

When we get hazy or unclear reactions in Gel, we use PEG, if neg, issue full XM compatible units - using PEG.

Check your Gel cards - is the level of liquid sufficient and even? Ortho probably won't agree (or at least put in writing) but you could try repeating the Gel panel after you spin the cards before using. Be sure your specimen is sufficiently spun too.

[JLF]

We find that tube method using PEG enhancement works well in identifying weak Kidd antibodies, as well as, newly forming Rh antibodies. That is our back-up to Gel.

[Elizabeth Gillis]

We have had similar results with gel. We send ours to reference lab, it usually comes back WARM Auto, Cold auto, occasionally an allo: Jka, Kell, C

[LABKING]

Does anyone have a cost analysis of antibody ID, reagent cost, time cost and amount of refrigerator space, necessary equipment, cell washer, limited ID and full service, etc

We are looking into doing our own AB ids, currently we send them out to another hospital which increases our TAT

[dcharland]

When we have weak reactions with Panel A and Panel B without a good answer to what the antibody is, we take an immucor panel and make a .8% diltuions of the cells and run that and typically we will get stronger reactions. We don't send out because the ARC in Baltimore uses tubes.

[David Saikin]

Labking - there are more issues than cost when doing your own Abid - like decreased length of stay for your patients. For the main question - I use Peg/tube as backup for unresolved gel id's. We recently had a pt with a 4+ anti-c and a Jka that was only 1+ with homozygous cells (could only find the anti-c with tubes). I have found more Kidds recently that I would not have found using tubes with peg (reactions in gel 1-2+). My experience is that gel reactions of 2+ or less are not discoverable using Peg or even enzyme pretreated with peg.

[Cathy]

When we have an inconclusive gel panel we will try tubes. I like to try a 3 cell screen with liss and another with peg. That way I can see how this antibody will react without using up too much sample. Then I have a better idea of what media to use on the panel. We have missed a couple of newly forming antibodies with gel, they came up great with liss. As long as we rule out all of the clinically significant antibodies (with gel and liss) we will transfuse crossmatch compatible, but if no additional information was gained from the liss or peg, give gel crossmatch compatible.

[khabeeb]

I was wondering what other labs are doing in these situations where you are using Gel>PEG>LISS. Do you run a DAT or Auto control, or both? And if you are switching methodologies, do you run the Auto control for each methodology (ie, run it in Gel, then PEG, then LISS)? We used to just run a DAT, and if we went through all our capabilities to ID an antibody and were unclear or uncertain, we'd send it to our reference lab. Now our supervisor wants us to add the Auto control to EACH antibody identification (whether it's a "simple" ID, or an ID where we need to move to another methodology). I can maybe see where in this may be helpful in the case where we are using multiple methodologies for antibody ID, but don't necessarily see the benefit on doing an DAT and Auto on a "simple" antibody ID. Maybe someone can enlighten me. Thanks!

[Eagle Eye]

Our primary method is gel. We run autocontrol with each panel and if AC is postive then we run DAT.

[AMcCord]

I ask for an auto with each test method used. That means we run the auto 3 times if we end up using gel, LISS and PeG. It is quite possible to detect an autoantibody with one method and not another. If you don't realize you are chasing a warm or cold auto in PeG because you only did the autocontrol with LISS (and it was negative), you may waste a lot of time and energy looking for a specificity that isn't there.

Remember that a warm or cold auto may not be reactive with all cells using a given method. It may look like it's a simple, straightforward allo on the antibody screen and even with the panel, except you just can't quite make it fit any particular specificity. I've seen a number of warms that behaved that way. A positive autocontrol suggests that what looks like a simple ID up front may actually be a warm auto. When I take things up a step to PeG, then I see broader reactivity or in a couple of cases, an actual warm auto specificity (like auto anti-K, auto anti-e). I think that doing the auto with the panel gets your investigation pointed in the right direction right from the start.

Edited May 28, 2008 by AMcCord
additonal comment

[tburns]

Our blood bank has been using MTS-Gel for about 5 years. Techs love it, especially on the off-shifts! However, occassionally we do use a secondary method-tube with

Peg as an enhancement and incubate for 30 minutes-to verify weak MTS-Gel results

(<1+). Our blood bank has found this seconary method to be as sensitive in ID'ing atypical antibodies. Initial parallel testing with tube vs MTS-Gel: techs found out that Peg/IgG results matched/verified much better than NHance or LISS. Also, cold antibodies seem to cause problems in MTS-Gel...prewarming the MTS-Gel cards does not seem to help much....techs convert back to tube/ prewarmed compatibility testing to verify if any 37C IgG antibodies are present as well as checking a 4C antibody screen.

[drsbright]

Our hospital system is seeing all sorts of aberrant results in GEL recently: mixed field reactions in multiple microtubes, Positive screening cells, with negative IDs, results inconsistent with patient history, results not reproducible, on and on...........

Ortho is defending their product MTS Gel, but the evidence is mounting against this system as being far too sensitive and unreliable.

While my colleagues in this e-forum have suggested multiple backup plans and methods for dealing with the GEL results, to keep retesting over and over is not feasible and too costly in terms of TAT and efficiency in the deparment. We find ourselves having to retest far too many patients and, as supervisor, I am flooded with calls, inquiries, and "what to dos"

If these large blood centers are jumping ship and going back to tube testing, there should be a message loud and clear to Ortho embedded in there.

While this is being sorted out, give me a supply of 12 x 75s and a marking pen.

Dr Stephen Bright

St Elizabeth Regional Health

Lafayette Indiana

[Mabel Adams]

We went to diluting our own screening cells (Immucor's) to 0.8% and our false positive rate in gel is now quite manageable.