Titer controls

[Sharon Ann]

I would like to hear what positive and negative controls are being set up when you do a titer on pregnant patients. Are if any controls are being done at all. Thanks!

[Malcolm Needs ☆]

If the titre is on a new patient, we (UK) would a NIBSC (National Institute for Biological Standards and Control) anti-D.
If it is a second or subsequent sample, we would titrate the stored (and frozen) previous sample, in parallel with the new sample.  If there was found to be a difference in titre, we would again use a NIBSC anti-D in parallel.

[John C. Staley]

If I remember correctly, back in ancient times, we did not include any control with the initial titer. (Probably because no one thought of it!) For any subsequent titers we would use a frozen sample from the previous titer.  

[Ward_X]

My facility's previous control was running the previous sample in tandem and the results had to agree within one dilution. This process is currently being remodeled.

[Darcy]

Have there been any updates to titer QC since these posts? We have an upcoming inspection next year, and we were told that we should be running QC for titers. Currently we do previous and current specimens in Gel on the Vision. Any standardized QC produced by suppliers? I would think the simplest and / or easiest to produce ourselves would be some kind of Anti-D value. Any suggestions?

[Kelly Guenthner]

On 11/22/2024 at 10:34 AM, Darcy said:

Have there been any updates to titer QC since these posts? We have an upcoming inspection next year, and we were told that we should be running QC for titers. Currently we do previous and current specimens in Gel on the Vision. Any standardized QC produced by suppliers? I would think the simplest and / or easiest to produce ourselves would be some kind of Anti-D value. Any suggestions?

We also do titers on the Vision.  We keep an aliquot of the previous titer, but only test it in parallel with the current if there is a significant difference to the current (titer jumps/drops 2 or more dilutions [The increase of 2 or more is our alert/critical value]).

We titer against screen cells, which are QC'd daily and do not do any additional titer QC.

[Ensis01]

For consistency you should probably have guidelines about the cells you select; i.e. stipulate for anti-D titers use R1R1 cells (or R2R2 or...), and for other antibodies stipulate the use of either heterozygous or homozygous expression of the antigen. 

[Malcolm Needs ☆]

Agree entirely Ensis01, BUT, even then there can be a considerable variation in antigen expression, and so I still maintain that the previous sample should always be run in parallel.

[Cliff]

Here are SOPs I used at my prior facility.  They are "older", but I think pretty good.E-5-3-_HTLA Titration.docxE-5-1-_Isohemagglutinin Titration.docxE-5-2_Prenatal Antibody Titration.docx

[Darcy]

'Here are SOPs I used at my prior facility.  They are "older", but I think pretty good.E-5-3-_HTLA Titration.docxE-5-1-_Isohemagglutinin Titration.docxE-5-2_Prenatal Antibody Titration.docx'

 

Cliff, I don't see where you list what the control material is for your prenatal titers? Do you use a commercial control obtained from a supplier or do you make aliquots from a high titer patient?

[Cliff]

4 hours ago, Darcy said:

'Here are SOPs I used at my prior facility.  They are "older", but I think pretty good.E-5-3-_HTLA Titration.docxE-5-1-_Isohemagglutinin Titration.docxE-5-2_Prenatal Antibody Titration.docx'

 

Cliff, I don't see where you list what the control material is for your prenatal titers? Do you use a commercial control obtained from a supplier or do you make aliquots from a high titer patient?

Shoot, those must have been before we implemented controls.

A senior tech takes an antibody (sorry, I don't remember which) and does a titer on it.  Then it's repeated by several other techs to ensure they get the same result (within one dilution).

That is then frozen (usually a unit from a donor).

When we get a patient titer, an aliquot of the control is thawed and run in parallel with the patient sample, and again, the control must match within one dilution.

Nothing is perfect, but I think this was a pretty good method.

It was developed by a member here (I believe), @Melanie Oliveira, an amazing tech I had the privilege of working with for decades.  Melanie, please correct my mistakes if this is off.