Patient is identified as having  “warmautoantibodies” in our lab with transfusion instruction to give C, E, K neg units. Patient was phentotyped for RH and Kell on the first work-up. When patient came back for a type and screen, 2 cell screen were 2+, ABID were all 1+ except for one cell being 3+. DAT was negative and when I performed tube screen and autocontrol, they’re both negative.
 

When I looked at the previous work-up, no transfusion has been done since 2018, screen and ABID also have panagglutination reactions. DAT and Tube screen were also negative. 
 

My supervisor asked me to do an elution and it came out with panagglutination reaction (3+ and 4+). Since patient also needed blood, I IgG crossmatched 4 units of C, E, K neg and they were all compatible.  

Our facility called it as warm autoantibody but it just didn’t sit well with me. Should I have done further testing to rule out if that one 3+ meant something else on the ID?

Thank you! 

Edited September 17, 2024Sep 17 by mondayw

At first I thought it might have been a high frequency antigen but it didn’t make sense as my crossmatches were compatible. 
 

I also thought it might be a cold antibody that reacts on IgG? I’m not very knowledgable on how cold antibody works and can’t back up how I came up with that 😅

I am kind of curious about is the crossmatches and ABID using the same method? 

Edited September 18, 2024Sep 18 by Yanxia

We use Lumena (solid phase) for the ID. Crossmatch is tube method IS, LISS 37C, IgG

I guess the solid phase is more sensitive to detect the auto in this patient. I will use the same method as detecting the antobodies to do crossmatch. Of course I will do saline and AHG crossmatch as well. Just my humble opinion.

Edited September 18, 2024Sep 18 by Yanxia
typo

10 hours ago, mondayw said:

Crossmatch is tube method IS, LISS 37C, IgG

Our SOP is to start with testing in gel (we use Vision Max) - if screen all pos, do panel, auto control and DAT.  if DAT is pos, do eluate - also tested on Vison Max.  if everything consistent with warm auto, we will then test patient plasma in LISS.  Often times the reaction is negative with LISS.  Apparently it has something to do with LISS and the sensitivity of the test......I don't know the exact science behind it, but,  if there are underlying clin. sig. ab's, they show in LISS where the warm auto does not.  If patient has been transfused in the last 120 days, we also will test the eluate in tube / LISS

Hi Yanxia, thank you for your recommendation. I did not know that you can actually do a solid phase crossmatch until now. However, it is not a part of our SOP in our lab. Might just try it next time and see how it works. 

Hi Bet’naSBB,

That’s the thing I’m confused though, how could we ID it as a warmauto if AC was negative? Also, was the elution necessary to perform since patient’s tube and DAT were negative since it was first identified? Is the elution result valid even if my DAT was negative? Patient was transfused years ago as well. 
 

Thank you! 

 

1 hour ago, mondayw said:

Hi Yanxia, thank you for your recommendation. I did not know that you can actually do a solid phase crossmatch until now. However, it is not a part of our SOP in our lab. Might just try it next time and see how it works. 

Maybe some day we can actually do it, 

My meaning was if we detected an antibody and didn't make sure it was auto or allo, we did crossmatch using a method that was sensitive, in case we missed it.

This a classic case of Sensitivity vs Specificity. Clinical assays (including those in the transfusion medicine arena) are often designed to be as sensitive as possible, especially those intended to be frontline screens. Nobody wants to miss anything. However, the downside of this approach is that sometimes specificity suffers - more positives are obtained than desired.

Solid Phase, Gel and PEG assays are super-sensitive, but may detect "nuisance" antibodies like weaker autoantibodies (warm and cold), or things like anti-P1, anti-Leb, or "HTLA-like" antibodies.

Less sensitive assays that employ no enhancement (saline) or thing like LISS are sometimes used strategically to avoid the nuisances. Many institutions have policies that allow the deliberate down-regulation of sensitivity to ameliorate such problems. For example, performing crossmatches in LISS rather than Gel. Certainly, there's a risk that something might be missed using a less sensitive assay, but I think it's important to realize that in years past, the use of those less sensitive assays didn't leave a trail of bodies.

In patients with long-term autoantibodies, it's not unusual for the autologous cells (DAT/autocontrol) to react weaker than Screening Cells or panel cells. The appears to be some kind of weakening of native antigens to which the autoantibody is directed. Sometimes, that may even mean the DAT is negative, but still yields a reactive eluate .

17 hours ago, mondayw said:

how could we ID it as a warmauto if AC was negative?

We do an AC in gel with every new ABID panel we have to run. (just with the first panel....not with EVERY one  )  Our SOP also states to do a DAT on all patients with new antibody ID's.  There are times when the plasma is only 1-wk2+ on all reagent cells that the AC is negative.  That's where the DAT comes in.....if the DAT is positive, (our gel Poly and IgG DAT's are often positive - but if we run the same test in tube, it will often be negative) we make an eluate and run it......which is often positive with all cells.

Again, I'm not sure of the "science" behind the "why" for the negative AC - my old brain simplifies it to thinking there may be some sort of dilution factor with the AC (addition of plasma and saline to make the suspension) causing it to be negative???  

Edited September 19, 2024Sep 19 by Bet'naSBB

1 hour ago, Bet'naSBB said:

We do an AC in gel with every new ABID panel we have to run. (just with the first panel....not with EVERY one  )  Our SOP also states to do a DAT on all patients with new antibody ID's.  There are times when the plasma is only 1-wk2+ on all reagent cells that the AC is negative.  That's where the DAT comes in.....if the DAT is positive, (our gel Poly and IgG DAT's are often positive - but if we run the same test in tube, it will often be negative) we make an eluate and run it......which is often positive with all cells.

Again, I'm not sure of the "science" behind the "why" for the negative AC - my old brain simplifies it to thinking there may be some sort of dilution factor with the AC (addition of plasma and saline to make the suspension) causing it to be negative???  

I tend to think that there are a number of factors affecting the reaction, such as changes to the pH, rather than just dilution, that would change the equilibrium constant within the Law of Mass Action that governs antibody/antigen reactions, but pH is only one of them.

On 9/19/2024 at 3:02 AM, exlimey said:

This a classic case of Sensitivity vs Specificity. Clinical assays (including those in the transfusion medicine arena) are often designed to be as sensitive as possible, especially those intended to be frontline screens. Nobody wants to miss anything. However, the downside of this approach is that sometimes specificity suffers - more positives are obtained than desired.

Solid Phase, Gel and PEG assays are super-sensitive, but may detect "nuisance" antibodies like weaker autoantibodies (warm and cold), or things like anti-P1, anti-Leb, or "HTLA-like" antibodies.

Less sensitive assays that employ no enhancement (saline) or thing like LISS are sometimes used strategically to avoid the nuisances. Many institutions have policies that allow the deliberate down-regulation of sensitivity to ameliorate such problems. For example, performing crossmatches in LISS rather than Gel. Certainly, there's a risk that something might be missed using a less sensitive assay, but I think it's important to realize that in years past, the use of those less sensitive assays didn't leave a trail of bodies.

In patients with long-term autoantibodies, it's not unusual for the autologous cells (DAT/autocontrol) to react weaker than Screening Cells or panel cells. The appears to be some kind of weakening of native antigens to which the autoantibody is directed. Sometimes, that may even mean the DAT is negative, but still yields a reactive eluate .

Hi Exlimey, this makes sense. Thank you for taking the time to explain it thoroughly. I appreciate it!