Reference lab workups

[Malcolm Needs ☆]

Hi David, I have been reading pathlabtalk for some time, and find the information very helpful. We use gel as the primary method. We have had a case where the gel screening was negative, but the patient had an anti Jka. I have spoken to colleagues at other labs who have similar experiences. There are some instances where the tube method by various potentiators will provide a stronger reaction than the gel method.

True. We also had an anti-Fya recently that we could not detect by gel, but could detect by LISS tube IAT at 37oC.

[David Saikin]

ijames

Kidds are notorious for their lack of aviditiy in any media . . . that's why we blood bankers love them.

[jill]

The reference lab I worked in performed all initial work ups using LISS. If negative, and a cold was suspected then a ficin panel

was tested. Also if LISS panel was negative a PEG screen was tested.

For a short while prior to this, only PEG was used and a 4:1 screen at IS, RT and 4C were set up as the initial testing.

A few of the submitting hospitals were requesting that our reference lab should acquire the gel methodology so we could duplicate

their results. Gel/ProVue were subsequently acquired in the ref lab. Our experience also in this reference lab was that the requesting facility would detect nnspecific reactions in gel and solid phase and we would get negative results using LISS, PEG, and

ficin treated reagent red cells.

My experience now with solid phase has been seeing what looks like an antibody detected reacting 3-4+ with all 14 wells with negative and then negative reactions using gel and tube. When rouleaux has been rule out, I suspect that there is an

antibody in the patient sample that is reacting against some unknown entitiy(stroma or chemical) that is affixed to the bottom

of the u-shaped well. Also with solid phase, newly forming antibodies whose make up is largely composed of the IgM isotype

(primary immune response) are on a few occasions missed using solid phase and then shown to demonstrate a clear pattern of reactivity in tube/LISS in which there is that valuable 37C reading. Also, the newly forming antibodies to not have the proper affinity

in the hypervariable reagions of the FAB portion of the immunoglobulin which does not result in its proper fit with its epitope. This

latter characteristic would result in a hard to or too weak to identify pattern using any methodology.

Bottom line is to use all methodolgy that is available for ID purposes. If time and cost start to be an issue then flow charting

based on what type of reactions seen with what methodolgy is of primary importance.

[jill]

We recently had an OB patient with no history of antibodies have a positive 2 cell screen in solid phase. All 14 wells in panel

were negative. The gel panel showed 3+ and 3- cells identifying an Anti-S. In tube/LISS this Anti-S reacted positive with

the S+ reagent cells and at AHG all these reactions were negative.

[jill]

The reference lab I worked in performed all initial work ups using LISS. If negative, and a cold was suspected then a ficin panel

was tested. Also if LISS panel was negative a PEG screen was tested.

For a short while prior to this, only PEG was used and a 4:1 screen at IS, RT and 4C were set up as the initial testing.

A few of the submitting hospitals were requesting that our reference lab should acquire the gel methodology so we could duplicate

their results. Gel/ProVue were subsequently acquired in the ref lab. Our experience also in this reference lab was that the requesting facility would detect nnspecific reactions in gel and solid phase and we would get negative results using LISS, PEG, and

ficin treated reagent red cells.

My experience now with solid phase has been seeing what looks like an antibody detected reacting 3-4+ with all 14 wells with negative and then negative reactions using gel and tube. When rouleaux has been rule out, I suspect that there is an

antibody in the patient sample that is reacting against some unknown entitiy(stroma or chemical) that is affixed to the bottom

of the u-shaped well. Also with solid phase, newly forming antibodies whose make up is largely composed of the IgM isotype

(primary immune response) are on a few occasions missed using solid phase and then shown to demonstrate a clear pattern of reactivity in tube/LISS in which there is that valuable 37C reading. Also, the newly forming antibodies to not have the proper affinity

in the hypervariable reagions of the FAB portion of the immunoglobulin which does not result in its proper fit with its epitope. This

latter characteristic would result in a hard to or too weak to identify pattern using any methodology.

Bottom line is to use all methodolgy that is available for ID purposes. If time and cost start to be an issue then flow charting

based on what type of reactions seen with what methodolgy is of primary importance.

[NatishaDixon]

We mix PEG with LISS and put it in Gel in hopes of detecting every antibody... just kidding.

[lacs]

Yes, we've got quite a few in our region, and we have seen an enormous increase in the number of samples sent in with "weak unidentifed antibodies" that we are just unable to confirm by all of our usual techniiques. Personally, I regard them as carp (whoops, I've mis-spelled that I think), because, whatever else they may be, they are NOT going to be clinically significant - so we just ignore them. We have not had a single case yet (I'm talking well over a hundred) that has caused ANY post-transfusion DAT positives yet (serological transfusion reactions), let alone a delayed or acute haemolytic transfusion reactions.

It is a case of sensitivity over sensibility!

:(:(:(

We run 3 screens-one w/o enhancement at IS, 37 and Coombs, PEG and GEL. Our problem is when it only reacts in GEL and looks like HTLAs. We are limited to what is tested. We do ficin, cord in gel and rarely DTT or titer since titration result is typically higher in gel than tubes. How are you all handling reactions in GEL only?

[Dr. Pepper]

We mix PEG with LISS and put it in Gel in hopes of detecting every antibody... just kidding.

We do the same but also in duplicate with PEG/LISS/GEL ficin-treated cells.

[Don B]

I became a member today specifically so I could look for answers to this question. With the ECHO on the market for an additional 2 years since this posted, has anyone developed a differing opinion to this question? I tend to agree with this position, but have staff who are uncomfortable when we see 1+ or 2+ solid phase reactivity and our reference lab (GEL) sends back reports of no antibody detected. Thanks!

[AMcCord]

We have not changed our policy regarding these types of reactions and have seen no adverse patient reactions related to them.

[Pony]

Yes, we've got quite a few in our region, and we have seen an enormous increase in the number of samples sent in with "weak unidentifed antibodies" that we are just unable to confirm by all of our usual techniiques. Personally, I regard them as carp (whoops, I've mis-spelled that I think), because, whatever else they may be, they are NOT going to be clinically significant - so we just ignore them. We have not had a single case yet (I'm talking well over a hundred) that has caused ANY post-transfusion DAT positives yet (serological transfusion reactions), let alone a delayed or acute haemolytic transfusion reactions.

It is a case of sensitivity over sensibility!

:(:(:(

I so agree with you on the sensitivity issue. 25, 30yrs ago we were not seeing this carp as you so elegantly put it and we didn't kill anyone. The quest to be the most sensitive product method is driving most hospital techs crazy. Like you, when I see a string of positives in gel or solid phase that do not react in PEG or LISS and show no specificity I KNOW IT WON"T HURT ANYONE IF IGNORED. I have not seen a single case of "unidentifiable reactions" in gel or solid phase cause a serologic reaction let alone an DHTR.

I swear the paranoia about "not missing a clinically-significant antibody" has been fostered by the manufacturers trying to expand their business base. Yes, if you have a weak Kidd or Duffy, it may well show up first in gel or solid phase and that is an advantage. But if if you don't see it until the patient has had a unit or 2, worst case scenario is a positive DAT, with future transfusions being antigen-negative. The patient never notices.

One of the cost issues is that once a positive reaction is reported in an antibody screen BB LIS here in the US, it will mandate a full crossmatch. That is a waste of time and money. At present, between SOPs and software, we have painted ourselves into a corner with these nonspecific reactions. Are we doomed to each slog through coming up with institution-specific testing algorithms or can we get some solid numbers published through lookbacks to show how oversensitive we are being?

What do the rest of you think?

[Gnapplec]

I agree with both Pony and Malcolm!!

As said above: the "sensitivity over sensibility" issue forces us to unnecessarily "paint ourselves into a corner" ...chasing nonspecific reactions.

Well said by both !!

[Barbarakym]

I am at a regular transfusion service. We use gel. I think a lot of gel reactions are junk. In our in house procedure our primary work is done in gel. If positive it is worked up in gel. If we rule out/in named AB (on panel). ThAt is ID. That works probably 96% of the time. In the rest either lists of spurious reactions after everything on panel is r/o. Low or hi incident evaluated. We call these junk reactions: non specific antibody. Cuz what r we going to do? AHG xm.

If we get what ortho calls mixed field. We go directly to tube. We have found most of these are colds. If neg by tube we call screen neg. no AB workup.

We send things needing eluates, hi incident AB, many AB showing to ref lab as we don't stock reagent for Those 1/100 patients.

Kym