We have a 14 year old girl admitted to the hospital with a hgb of 5.0. In gel her antibody screen is 3+ in all cells. Her direct coombs in gel is 4+. In tubes her antibody screen is negative (using LISS) with a 2+ auto control. Her direct coombs in tubes is 2+ IgG and 1+ C3. I crossmatched units in tubes and they are negative. Is it safe to transfuse?

Antrita

did you try to crossmatch in Gel?

I'm assuming you mean that the panel cells were all positive.

Sickle Cell patient?

Was the patient recently transfused?

Was an eluate performed, and if so, any reactivity seen?

Generally, if the patient has a warm auto ab (no specificity seen), then using LISS for screens and crossmatches is acceptable at our facility.

We have a 14 year old girl admitted to the hospital with a hgb of 5.0. In gel her antibody screen is 3+ in all cells. Her direct coombs in gel is 4+. In tubes her antibody screen is negative (using LISS) with a 2+ auto control. Her direct coombs in tubes is 2+ IgG and 1+ C3. I crossmatched units in tubes and they are negative. Is it safe to transfuse?

Antrita

With the caveats given by Lcsmrz in mind (particularly the eluate, if the patient has recently been transfused), I would not hesitate to give blood that has been cross-match ed by LISS tube IAT in this case.

This is a comparatively common finding, and we cross-match by LISS tube IAT on many, many occasions under such circumstances, and have never seen any problems with the patient afterwards.

:D:D:D

I think if she had not transfused it is safe to give tube compatible units.

Whenever I find a warm auto in gel I immediately switch to PeG. Can usually absorb out any auto (if not recently transfused) and give absorbed plasma compatible red cells. You should have no problems . . . LISS is fine too.

I agree with Malcom, we do this often.

Whenever I find a warm auto in gel I immediately switch to PeG. Can usually absorb out any auto (if not recently transfused) and give absorbed plasma compatible red cells. You should have no problems . . . LISS is fine too.

I don't understand this. Immucor states that PeG enhances reactions. How does it "absorb out any auto" ? Pardon my ignorance.

Thank you,

Liz

The only thing I can figure is that it enhances uptake of the autoab onto the pt's own cells during the absorption phase.

I think it is preferable to use tubes with PEG or LISS if these are compatible rather than fooling around with absorptions. This is, as others have noted, a pretty common occurrance esp in the sickle cell population.

The only thing I can figure is that it enhances uptake of the autoab onto the pt's own cells during the absorption phase.

So you would perform an elution and adsorption procedure, right?

Liz

We are actively looking at the available automated platforms, all of which seem to be more sensitive than LISS/tube, and I find this thread and many similar others fascinating in that gel and solid phase are sometimes too sensitive, picking up unwanted autoantibodies, colds, and some "unknown solid-phase (or gel)-reactive antibodies of undetermined specificity" that aren't observable with any other methodology. And, once we've done as best we can to see if there's anything there we can pin down as being really significant, everyone's solution seems to be to use crossmatch-compatible blood by that technology, oand if that doesn't work to back off to a less sensitive methodology.

It reinforces how nebulous and subjective our definition of "compatibility" is. Imagine, if you will, the following problem patient from h**l, who has a warm autoantibody, anti-IH, anti-P1, anti-Lea and Leb, anti-Sda, anti-Chido and a cold alloantibody of undetermined specificity. So we autoadsorb the serum, then REST-adsorb it, then neutralize it with commercial P1 and Le substances, then urine-neutralize it, then plasma-neutralize it, then prewarm it, then incubate it with the donor's cells without enhancement media for 60 minutes, then wash and Coombs it, then call and say the blood's ready. The doctor says, "Boy, that took a while. But is it compatible?" And you say to him "Sure!" and hang up and walk away and mumble to yourself "Kind of....sort of...."

..Oh, how true!!! Unfortunately.

Liz :disbelief:disbelief:disbelief

Might as well crossmatch with saline after all that! We don't call it compatible if we have to do any adsorptions. Any adsorption has the chance of removing something significant. Of course, if you do any neutralizations, you have to make sure you did not dilute out anything significant.

Perhaps we are just fooling everyone by calling it "compatible." This word implies that it is somehow safe. Transfusing blood is never safe, it is just a calculated risk and certainly better than exsanguinating!

Might as well crossmatch with saline after all that! We don't call it compatible if we have to do any adsorptions. Any adsorption has the chance of removing something significant. Of course, if you do any neutralizations, you have to make sure you did not dilute out anything significant.

Perhaps we are just fooling everyone by calling it "compatible." This word implies that it is somehow safe. Transfusing blood is never safe, it is just a calculated risk and certainly better than exsanguinating!

What do you call such a blood unit?

Thanks

Liz

We call them "incompatible with neat plasma, compatible using autoabsorbed plasma". The MD signs that he is transfusing incompatible red cells and has been informed of the nature of the incompatibllity.

Thank you, Dave

Liz, and since there are no smilies, a pink dolphin:

What do you call such a blood unit?

Thanks

Liz

We call them "incompatible." We inform the doctor of the outcome of the adsorption and give cautions about the risk of transfusion. They get to decide whether to transfuse or not, which they usually do. It is usually not too dangerous in a non-sickle patient. The old adage that transfused units last as long as autologous cells in a patient with warm auto antibodies and no underlying allos still holds true.

Hey Liz,

You answered your own question;"PeG enhances reactions." PeG is polyetholene glicol (spelling?); that's right; anti freeze. Now what we use as a reagent in the Blood Bank is not exactly the same as what we use in our cars but the same principle is applicable; that is polyetholene glicol breaks up water. Water in our reaction volume has the ability to suppress the over mulecular charges present at the antigen epitope and the antiboby variable region by binding to individually charged particles at each site and therefore rendering the particles more nutral. PeG, by beaking up water allows these charged particles to maintain their complete charge and therefore enable stonger bonding between opposite charged particles comprising each site of the antigen epitope and the antibody variable region for both IgG, and apparently IgM class antibobies, according to the post given by David Saikin. Although it's late I hope this helps.

This is a response to Liz's post to David Saikin about PeG. I overlooked the "Reply with Quote" icon.

Edited July 31, 201015 yr by rravkin@aol.com

We are actively looking at the available automated platforms, all of which seem to be more sensitive than LISS/tube, and I find this thread and many similar others fascinating in that gel and solid phase are sometimes too sensitive, picking up unwanted autoantibodies, colds, and some "unknown solid-phase (or gel)-reactive antibodies of undetermined specificity" that aren't observable with any other methodology. And, once we've done as best we can to see if there's anything there we can pin down as being really significant, everyone's solution seems to be to use crossmatch-compatible blood by that technology, oand if that doesn't work to back off to a less sensitive methodology.

It reinforces how nebulous and subjective our definition of "compatibility" is. Imagine, if you will, the following problem patient from h**l, who has a warm autoantibody, anti-IH, anti-P1, anti-Lea and Leb, anti-Sda, anti-Chido and a cold alloantibody of undetermined specificity. So we autoadsorb the serum, then REST-adsorb it, then neutralize it with commercial P1 and Le substances, then urine-neutralize it, then plasma-neutralize it, then prewarm it, then incubate it with the donor's cells without enhancement media for 60 minutes, then wash and Coombs it, then call and say the blood's ready. The doctor says, "Boy, that took a while. But is it compatible?" And you say to him "Sure!" and hang up and walk away and mumble to yourself "Kind of....sort of...."

DR P,

You have acheived an in formative and comical post here; and I am still laughing because it's true to real life! After performing all of these in-vitro manipulations the term compatibility becomes very obscure. And even if we attach the specific manipulations when reporting compatibility, at the end of the day we are still left with the same obscurity. It's amazing how complex things suddenly become. Thank you.

Two more questions now that I believe I have understood how PeG functions and how it is used:

1. PeG enhances adsorption on untreated autologous cell; one usually pre-treats autologous cells to remove the Abs sensitizing the auto cells to allow for adsorption. If the untreated cells are well sensitized (Ags well saturated with Abs), how can they adsorb the autos even with PeG... are there any free sites?

2. Why would PeG cause us to miss allos.. why would using PeG do that?.. Is it due to the dilution?

Thanks

Liz

There may be 2 mechanisms (I think): one may be dilutional, a weak ab may be diluted out with the 1:1 Peg/plasma dilution (though I would think you would miss it anyway if you used PeG); second is that PeG may not enhance all abs. BUT, there is no perfect method - there is always give and take with any of the enhancement media.

Liz-

I believe David refers to AABB method 4-10

Polyethylene Glycol Adsorption

when was the last time she was transfused? Are you planning on doing an eluate to rule out alloantibodies? Do you normally have such discrepancy with gel and tube? I don't think I would transfuse her until I did some kind of workup.

I apologize asking again but how does this happen?

"PeG enhances adsorption on untreated autologous cell; one usually pre-treats autologous cells to remove the Abs sensitizing the auto cells to allow for adsorption. If the untreated cells are well sensitized (Ags well saturated with Abs), how can they adsorb the autos even with PeG... are there any free sites?"

Thank you

Please forgive my insistence on understanding the mechanism.

:blowkiss:

Liz