Misc Gel Reactivity: Grrr!

[ElinF]

Ok, we have recently been getting burned by this annoying issue. Can I get procedure suggestions I can give to my staff to deal with this. They always ask me and we always have to feel our way though it.

Basically we get a positive gel screen. Do a gel ABID panel. Sometimes positive with no clear pattern (is it an antibody, or the start of one or not?) sometimes negative, however we don't want to ignore the positive screen.

We then usually go to an immediate spin tube screen then refrigerated for 10 minutes to identify any colds. And then rule out. Sometimes we repeat with new specimen, but mostly it does the same.

Is this all we should be doing? Is this good enough? I am so afraid we are going to get complacent with this misc reactivity and miss something and I truly do not want to do that obviously, but we have had like 6 of these since Christmas (we are a small lab) and I am afraid it is desensitizing people to true positive results.

Any suggestions would be helpful!

Thanks!

elin

[tbostock]

Yes, we are frustrated too, and I also worry about the complacency issue. We do a gel panel every time. If it's negative, we're done (and suspect that the screening cells are starting to get contaminated; usually happens as they get near expiration date). If panel is positive we go through the usual: rule out clinically significant alloantibodies, do a refrig tube screen if we think it looks like a cold agglutinin, tube testing if it looks like rouleaux. If weak non-specific, and everything is ruled out, we do Coombs' crossmatches just to be safe.

[clmergen]

That is exactly how we dealt with those non-specific solid phase antibodies also.

[ElinF]

Thank you so much. At least I can tell them that they are not alone!

[JOANBALONE]

How long do you continue to do AHG crossmatches, until the next screen is negative?

JB

[ElinF]

We do not yet do electronic crossmatches, so we always do AHG crossmatches. Most of the time our units are compatible. It is just the screen cells that are positive.

[Malcolm Needs ☆]

I have a feeling that many commercial firms have gone too far down the road with sensitivity of their tests, without taking into account specificity.

We get, quite literally, about 200 or so samples every year at the Tooting Reference laboratory from our hospitals who are using certain technologies that, try as we might, we detect nothing in. However, when we perform the tests using the same technology, there are the non-specific reactions, that are totally clinically insignificant.

Not only does this mean a whole load of unnecessary work for both the hospitals and us, but also delays transfusion of the patient unnecessarily.

[galvania]

When you say gel, which gel are you using?

[David Saikin]

We have noticed sporadic rxs with Ortho's screening cell II. I also get reference work due ti this same phenomenon. I have found that in ~80% of cases, enzyme pretreatment will remove the reactivity. HOWEVER, I have also found that if I run an Ortho panel all the R2R2 cells will be reactive AND the pt is invariably E= AND if I take a non-Ortho 3% panel, make it 0.8% it will be non-reactive unless I enzyme pretreat it, in which case most of the R2R2 cells will be reactive. Natural anti-E? I have to call it such. I have said for years that both gel and capture are way too sensitive, but . . . what do I know?

[ElinF]

We use Micro ID typing systems from ortho. I want to say that it is mostly screen cell 2 as well, but sometimes it is 1 and 2. Usually only 1+ or so, but you can't ignore that. We don't have the ability to enzyme pre-treat. I suppose we are getting pretty good a these since we are starting to get them more often. We never really used to get these in this abundance, it seems like in the last year or so it has really increased.

Speaking of natural anti-E we had a pregnant woman form anti-E so we were concerned with her titers the whole pregnancy. They never went up but the funny thing is her husband was big E negative, she was obviously big E neg.....sooooo how could the baby be big E positive giving mom the opportunity to produce Anti-E. Well, the baby was big E neg too and mom just had anti-E for whatever reason. (And we ruled out the possibility of a possible switch-a-roo on the father as she was close friends with one of the techs). So that was interesting. I did learn at a Red Cross event that naturally occurring big E has been seen during pregnancy. I was like viola! there's my answer!

[Brenda K Hutson]

First, just to clarify; are the problems you are seeing, a hazy look? Diffuse agglutination (so does not look quite normal)? The "false mixed field halo" look? We do get these from time to time. I no longer immediately jump to a panel but it is a case by case basis.

The ones that look hazy, I have the staff repeat with PeG. If the PeG screen is Negative, we call it Negative. The ones with diffuse agglutination often turn out to be a Cold or Rouleaux (so if non-group O, I ask them to see if there is rouleaux in reverse type; can also check I.S. crossmatches). If suspect it could be due to rouleaux, will probably have them perform PeG instead of a complete panel (but of course if PeG is positive, we will perform a panel). If I suspect a Cold, will do a Cold Panel before anything else. That false halo seems to usually be due to some fibrin (which yes, can be present in an EDTA) and when I see that wimpy, incomplete ring, I call it Negative. But all of those require enough experience to "suspect" that it is not true agglutination (experience which you and your staff may have).

But being a small Lab, don't know if you keep PeG in stock? Could also use LISS; it is just my preference to use PeG since it is a stronger potentiating media. However, if you suspect a Cold, LISS would probably be better anyway. As I said, I evaluate some of these on a case by case basis. But you are correct; it can be frustrating.

Now all of that being said, if we have a particular Lot # for which we are just getting too many False Positives, I call Ortho and report it; if bad enough, I ask for a new Lot #. Have had those occassions throughout my 27 years whether with Ortho, Immucor or some other company; and at times, in tube testing (not just GEL).

Brenda Hutson, CLS(ASCP)SBB

Ok, we have recently been getting burned by this annoying issue. Can I get procedure suggestions I can give to my staff to deal with this. They always ask me and we always have to feel our way though it.

Basically we get a positive gel screen. Do a gel ABID panel. Sometimes positive with no clear pattern (is it an antibody, or the start of one or not?) sometimes negative, however we don't want to ignore the positive screen.

We then usually go to an immediate spin tube screen then refrigerated for 10 minutes to identify any colds. And then rule out. Sometimes we repeat with new specimen, but mostly it does the same.

Is this all we should be doing? Is this good enough? I am so afraid we are going to get complacent with this misc reactivity and miss something and I truly do not want to do that obviously, but we have had like 6 of these since Christmas (we are a small lab) and I am afraid it is desensitizing people to true positive results.

Any suggestions would be helpful!

Thanks!

elin

[KKidd]

When we get weak or ambiguous results(don't you just ove those big words!) I have the techs centrifuge the sample again and repeat the screen by incubating for 30 minutes. Sometimes those reactions that I like to call Anti-CRAP or Anti JJ(just junk) will get weaker or disappear. If the antibody ID yields inconclusive results and all clinically significant allo-antibodies can be excluded, we call it a day and transfuse AHG crossmatch compatible blood.

Also, at Ortho's suggestion, we started keeping our reagents in a black file box to protect them from light. That seemed to help.

:juggle::juggle::juggle::peaceman::bye:

[Brenda K Hutson]

You are correct about Ortho's suggestion. We cut the tops off of 3 sets of boxes (we keep 3 racks) and place them upside down over the Screening Cells so they are covered at all times. This does seem to have cut down on some of those "scummy" reactions.

I don't see GEL as being "bad" just because we get this occassional junk; it is just such a different medium than other protocols so it has it's own unique set of pros and cons. I still love it!

Brenda Hutson

When we get weak or ambiguous results(don't you just ove those big words!) I have the techs centrifuge the sample again and repeat the screen by incubating for 30 minutes. Sometimes those reactions that I like to call Anti-CRAP or Anti JJ(just junk) will get weaker or disappear. If the antibody ID yields inconclusive results and all clinically significant allo-antibodies can be excluded, we call it a day and transfuse AHG crossmatch compatible blood.

Also, at Ortho's suggestion, we started keeping our reagents in a black file box to protect them from light. That seemed to help.

:juggle::juggle::juggle::peaceman::bye:

[Bill]

David, you are sooooooo correct when you say gel and capture are toooooooo sensitive. It is that reason that we can not remove tubes from our testing. Too bad there is not automated tube testing!!!

[Brenda K Hutson]

This is just my opinion, but again, there are pros and cons to every system. In my experience, I think GEL is somewhere inbetween LIS and PeG in reactivity. A big plus is that it takes away the variability of grading reactions in tubes. While there are some situations in which is seems too sensitive, I don't think it outways the pros.

Again, that is just me....

Brenda Hutson, CLS(ASCP)SBB

David, you are sooooooo correct when you say gel and capture are toooooooo sensitive. It is that reason that we can not remove tubes from our testing. Too bad there is not automated tube testing!!!

[ElinF]

I have seen the halo reactions and the hazy reactions and these are not it. These positive results are usually 1+ and are very believable. We have LISS and use that for tube if we need to. Thank you for all your suggestions! Unfortunately I am finding that it will usually be looked at on a case by case basis.

First, just to clarify; are the problems you are seeing, a hazy look? Diffuse agglutination (so does not look quite normal)? The "false mixed field halo" look? We do get these from time to time. I no longer immediately jump to a panel but it is a case by case basis.

The ones that look hazy, I have the staff repeat with PeG. If the PeG screen is Negative, we call it Negative. The ones with diffuse agglutination often turn out to be a Cold or Rouleaux (so if non-group O, I ask them to see if there is rouleaux in reverse type; can also check I.S. crossmatches). If suspect it could be due to rouleaux, will probably have them perform PeG instead of a complete panel (but of course if PeG is positive, we will perform a panel). If I suspect a Cold, will do a Cold Panel before anything else. That false halo seems to usually be due to some fibrin (which yes, can be present in an EDTA) and when I see that wimpy, incomplete ring, I call it Negative. But all of those require enough experience to "suspect" that it is not true agglutination (experience which you and your staff may have).

But being a small Lab, don't know if you keep PeG in stock? Could also use LISS; it is just my preference to use PeG since it is a stronger potentiating media. However, if you suspect a Cold, LISS would probably be better anyway. As I said, I evaluate some of these on a case by case basis. But you are correct; it can be frustrating.

Now all of that being said, if we have a particular Lot # for which we are just getting too many False Positives, I call Ortho and report it; if bad enough, I ask for a new Lot #. Have had those occassions throughout my 27 years whether with Ortho, Immucor or some other company; and at times, in tube testing (not just GEL).

Brenda Hutson, CLS(ASCP)SBB

[CM2]

We sometimes see reactions due to the preservative in the prediluted 0.8% cells. Sketchy positive reaction in the 0.8% initial screen, weak sketchy reactions in the 0.8% commercial panel. But if you take 3% cells (either screen or full panel) and dilute them down to 0.8% with MTS diluent 2 (dil 2+ if making enzyme panel) you get no reaction at all. We will document the results of both the original screen and inhouse diluted screen in our system and then result the screen 'negative with inhouse cells' and make notes to the tech to use prediluted screen cells in the future. This method assumes you run QC Pos and neg with your self prepared diluted cells that works, and that none of the self diluted cells show any positive reactions - if so you must assume real antibody present and do further workup/ruleout.

[Brenda K Hutson]

Just one other thought I had after sending my reply. In my 27 years, GEL or Tube, we do have the occassional Lot# that has some nuisance antigen that results in a lot of positive reactions one would rather not see. With GEL in particular, just in the past couple of years, there are have been a couple of instances of a Lua on one of the screening cells. While this is a Low Incidence and one would not "expect" it to cause many problems, surprisingly, it has! So if none of the cells on the panel you use have Lua, it would appear to be unexplainable. No doubt this could occur with other Low Incidence also, In addition, throughout the years, there is the occassion that the Manufacturer inadvertently uses a cell that has a strong I or P1. There are other explanations but I'm sure you get my intent. And yes, those appear as true agglutination and must be investigated as such.

Brenda Hutson

I have seen the halo reactions and the hazy reactions and these are not it. These positive results are usually 1+ and are very believable. We have LISS and use that for tube if we need to. Thank you for all your suggestions! Unfortunately I am finding that it will usually be looked at on a case by case basis.

[Malcolm Needs ☆]

Well, the Lu(a) antigen isn't that much of a low incidence antigen Brenda. It's about 8% in the White population and about 5% in the Black population (not far off K+ in the White population and definitely more common than K+ in the Black population). It is just that anti-Lua is (comparatively) common ("naturally" occuring), and we don't really want to detect it because it is clinically benign.

[mrmic]

Again, Mr. Needs is right on. One must remember the gel tube is nothing but a minaturized LISS tube test and you will possibly get non-specific reactivity that is not clinically significant. I would say, with some reservations, that a clinically significant antibody would have a much more clear cut reactivity pattern. As far as the "naturally occuring" aniti-E, maybe it is really "E-like" and could be absorbed on E negative cells? We have seen other antibodies during pregnancy develop with the father and child negative for the corresponding antigen...good student project some day.

[Brenda K Hutson]

Malcom, it is only a higher % in England; it is Low Incidence in the USA (Ha Ha...just kidding ). Don't you ever take a break from this website and catching our errors?

You are of course, correct in the strictest sense of the phrase Low Incidence . In my mind, as I was writing it, I was thinking about the fact that it is not usually on Screening Cells, and sometimes not even on Panels. So when my staff get a positive cell that is just "hanging out there all by itself," I tell them to look at Low Incidence Antigens (maybe I won't list those again...just in case )

Brenda Hutson

QUOTE=Malcolm Needs;35749]Well, the Lu(a) antigen isn't that much of a low incidence antigen Brenda. It's about 8% in the White population and about 5% in the Black population (not far off K+ in the White population and definitely more common than K+ in the Black population). It is just that anti-Lua is (comparatively) common ("naturally" occuring), and we don't really want to detect it because it is clinically benign.

[AMcCord]

When we used gel, we resolved those suspect 1+ reactions with negative/inconclusive gel panels by repeating the screen with PeG. If the repeat screen was negative, we reported the screen as negative. The last 18 months we used gel, we stopped using pre-diluted cells and made up fresh 0.8% cells from 3% cells daily (yes, it was a bit of a pain!). After that we had much less trouble (which made the daily dilution of the screen cells less painful).

[galvania]

'One must remember the gel tube is nothing but a minaturized LISS tube test and you will possibly get non-specific reactivity that is not clinically significant'. Quote from Mrmic above.

Well, mrmic, that's not really true. In a LISS Coombs tube test, you have cells suspended in LISS and plasma only; after incubation you wash the cells and add your Coombs. In the gel test, you have a tube filled with gel which itself is mixed with the Coombs reagent. The cells and plasma, after being incubated in the reaction chamber at 37° then come into contact with the Coombs during centrifugation. The gel separates out agglutinated cells from non-agglutinated ones. There is no wash phase. Couldn't really be more different.......

[BankerGirl]

We also stopped using the prediluted cells for our antibody screens. It isn't much of a pain to dilute up the cells compared to all the unnecessary panels we were working up. Plus, we changed manufacturers because the Ortho cells had so many Bg antibodies on their screening cells. Much happier now!

[Cheryl]

We too have seen these troublesome reactions with Ortho Screening 0.8% Cel 2. Mostly as the vials are getting old. It makes a tremendous difference to protect these vials from light and refrigerate when not in use. If I get these reactions, I will take out a new set of screening cells and most of the time the reation is not there.