Dilution of Ortho QC Confidence antibody for antibody screen QC

[emergency room]

I am revising the daily reagents QC SOP and was wondering if anyone dilute their Ortho confidence antibody

when QCing their tube antibody screen cells and gel screening cells. If so, at what dilution? and if this

is prepared daily when running QC or prepare in batches.

Emergency room

[Auntie-D]

Please don't do this!

[jayinsat]

Why would you dilute it?

[David Saikin]

You shouldn't have to dilute the QC ab for tube testing. 

[Eagle Eye]

You should validate your own dilution.

We validated few dilutions then ran controls fro two weeks and based on the results decided that we will prepare and use the dilution for a week. 

[Auntie-D]

If you alter the controls in any way and there is an issue the manufacturers will wipe their hands of it...

[Joanne P. Scannell]

No diluting for Tube Testing.

BUT we do have to dilute the Confidence Antisera for manual MTS testing otherwise the result is 4+ which is useless.  At this time, we add 1mL Confidence Antisera to 9mL 6% Albumin (I prefer that to saline, but perhaps saline would work).  This dilution produces a 2-3+ result in MTS.

I must add that I am in the process of decreasing this so that we get 1+ results in response to a lot of chatter out there about 'testing vs a weak antibody' (CAP)... I don't see 2-3+ as 'weak'.  So, this dilution will be changing.

But it's a start ...

[marvy1]

We do 1:20 dilution of ortho QC for gel using Gel diluen. If you are not diluting then (in my opinion) you are not going to catch problems b/c the antibody is so strong in the QC kit. By diluting it down to give you a 1-2+ reaction, you are more likely to see problems should they occur.

[DebbieL]

I agree that the control needs to be diluted for gel testing. Seeing 4+ in gel doesn't tell me if the screening cells will detect weak reactions. We dilute until we get 1-2+ reactions.  

 

Is there some regulation that says we CAN'T dilute the antisera for QC?

 

So many regulations, so little time!

[kirkaw]

We dilute our Ortho Confidence antibody to QC manual gel as well. I believe this was a manufacturer's suggestion when we purchased the gel workstation.

[SMILLER]

Our situation is a bit different here.  But we do use our regular ABO/Rh/tube screen QC material (Immucor cor QC) diluted for our gel screen QC. 

 

We add 10 ul of the QC antisera to 8 drops of albumin to get a 2-3+ reaction.  We have had several inspections and this has never been an issue as far as the regs go.

 

Scott

[DebbieL]

Thanks Scott. We also use the the Immucor cor QC for our Echo. I never really thought about using it for my daily gel QC. We have just used diluted antisera. Thanks for the instructions. I am going to give this a try.  I think CAP will be all up in our QC with lots of scrutiny starting next year because of IQCP and I want all my ducks in a row long before then.  

[SMILLER]

I believe it was our Ortho tech rep who helped us with this method.  You probably should check with your rep before writing a proceedure if you are going to do this.  Like any new process, you will at least need to have documentation that you get consisitant repeatable results before using it as QC.

 

Scott

[DebbieL]

Yes, that is our life. Validate everything, keep the records and be able to find them when an inspector asks to see them. Document, document, document!

[emergency room]

Hey everyone... thanks all for your input. Do you all re check the dilution when change to a new lot of the

Ortho confidence QC antibody? or the particular dilution always work between lot to lot?

Emergency room

[Auntie-D]

Why are your manufacturers even producing QC material that is so strongly reacting? In the UK our reactivity is usually 2-3+ never more and if you get a 1+ reaction you query whether your QC is 'going off'. 

 

Could you not raise it with the manufacturers that what they are producing really isn't fit for purpose? As soon as you start fiddling with it, the manufacturer absolves themselves of all responsibility, which really isn't a good position for the lab to be in.

[Joanne P. Scannell]

Hey everyone... thanks all for your input. Do you all re check the dilution when change to a new lot of the

Ortho confidence QC antibody? or the particular dilution always work between lot to lot?

Emergency room

YES!  And again, with documentation of the check.

[BBfuntimes]

No diluting for Tube Testing.

BUT we do have to dilute the Confidence Antisera for manual MTS testing otherwise the result is 4+ which is useless.  At this time, we add 1mL Confidence Antisera to 9mL 6% Albumin (I prefer that to saline, but perhaps saline would work).  This dilution produces a 2-3+ result in MTS.

I must add that I am in the process of decreasing this so that we get 1+ results in response to a lot of chatter out there about 'testing vs a weak antibody' (CAP)... I don't see 2-3+ as 'weak'.  So, this dilution will be changing.

But it's a start ...

What is the expiration of your diluted antibody?

[JHH1999]

Why are your manufacturers even producing QC material that is so strongly reacting? In the UK our reactivity is usually 2-3+ never more and if you get a 1+ reaction you query whether your QC is 'going off'. 

 

Could you not raise it with the manufacturers that what they are producing really isn't fit for purpose? As soon as you start fiddling with it, the manufacturer absolves themselves of all responsibility, which really isn't a good position for the lab to be in.

Basically some labs struggle with QC and the actual intent. They also may have issues with staff not detecting weak reactions, specifically in tubes. Manufacturer's in the US tend to make QC material so strong that it is less likely to be missed. The result is the manufacturer avoids product complaints and the labs do not have QC failures requiring investigation. However, the intent of QC is missed in my opinion. QC should ensure your test system is capable of detecting weak reactions. 

 

QC products manufactured where I work were developed (IgG coated control cells and Daily QC Kit) to detect if there is a weakness rather than just checking a box that QC has been done.  

[Dansket]

Another approach is to retrospectively review the strength of agglutination observed in patients with a positive antibody screen over a period of time.  I can tell you that 70-80% of all my positive antibody screens are weakly reactive (1+ to 2+) despite daily QC that reacts strongly (3+ to 4+).

[mollyredone]

So do you think that you have to prove through daily QC that it detects weak reactions when you have a patient that reacts weakly to show that it does?  I didn't see anything in the package insert that mentioned gel, just tube testing, and we get a 2+ with tubes, which we only do if we have to do a tube screen.  Our primary method is gel.  Now I even wonder if this QC kit is appropriate for manual gel, since their methodology says tubes, or for automation, follow manufacturer's instructions.

[Dansket]

We use ORTHO's Alba Q-Check Simulated Whole Blood Controls.  This set of 4 QC vials is designed for the Gel method, both manual and automated.  However, all the antibodies (anti-A, anti-B, anti-D, anti-c) in this QC system react strongly (3+ to 4+).

Edited October 23, 2015 by Dansket

[BBfuntimes]

Would anyone share their "recipe" for 6% albumin and the expiration once it's made?  What do you dilute with?  Blood bank saline, another type of saline?  New policies, I wanna get em right!

[TreeMoss]

We make our own QC using the Ortho reagents, so we dilute up the anti-D and anti-c for use in tube and gel methods.  The aliquots are stored in our freezer. The tube method is just a 1:50 dilution of anti-c, and we dilute that and the anti-D up further for use when QCing the gel card/reagents.  We have done this forever (it seems) and have never purchased the QC reagents.  It works really well.

[DebbieL]

We also make our own diluted daily QC for testing in gel. We dilute antisera (anti-D and anti-c)  with about 7 ml of 6% albumin until we get about 1+ reactions in gel. We put it in a cleaned reagent bottle, store at 1-6C and use until it is gone and then mix up more.  We have done this for years without an issue. When we get low, we mix up another batch.

 

I think the main object is to make sure the gel cards and daily reagents used will detect an antibody with each cell used for antibody detection (TRM.31400). I consider my homemade brew a "weak patient antibody" and the QC part is I can detect the weak antibody with the gel cards and screening cells I am using that day.

 

This was started by my predecessor years ago and I have continued the process. I really don't want to spend a small fortune on a commercial QC product if I can make it up myself and still satisfy the standard. I do think the inspectors will be all up in our QC because of IQCP so I want all my ducks in a row.