[Histonet] shelf life of working antibody solutions in IHC

[Tony Henwood]

In Australia, we have evolved from Prescriptive accreditation (following the standards) to Risk-based accreditation where it is more important to assess the risk of a laboratory process rather than only meeting a list of rules, since following a list of rules is often not in the patient’s nor in the community’s interest.

Years ago, I battled with our accreditation organization over the risk involved in fridge temperature recording, presenting evidence that continuous digital monitoring (with an alarm system) was less risky than recording max/min temperatures daily (eg what happens when the lab is not manned during Christmas holidays and weekends?).

The excessive cost involved in automatically disposing of expired antibodies is wasteful. Continuous monitoring as well as preventative practices such as preservatives (azide, procillin, etc) and pH monitoring with phenol red greatly reduces the risk.

As presented in the paper, many working dilutions survive without contamination for many years. For example, factor 8 (21 years), factor 13a (19 years) and epithelial membrane antigen (17 years). There were no failed verifications and to date, the average life after expiration was 6 years; eight antibodies exceeded 6 years. All the other antibodies would probably have similar survival times but were exhausted before reaching these times.

Regards,

Tony Henwood MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) (Retired)
Principal Scientist, the Children’s Hospital at Westmead (Retired)
Adjunct Fellow, School of Medicine, University of Western Sydney.

From: Gudrun Lang<mailto:gu.lang at gmx.at>
Sent: Sunday, 2 July 2023 7:26 PM
To: 'Tony Henwood'<mailto:afhenwood at outlook.com>
Subject: AW: [Histonet] shelf life of working antibody solutions in IHC

Dear Tony,
thank you for the interesting article. It reflects my personal experience. Nevertheless accreditation rules overrule the experience and in an diagnostic lab we have to discard the reagenses.

My question regards more the practical approach with working solutions.
What is your experience how long the working solutions are „good enough“ for using.

Thank you very much and kind regards
Gudrun

Von: Tony Henwood [mailto:afhenwood at outlook.com]
Gesendet: Samstag, 1. Juli 2023 23:41
An: Gudrun Lang
Betreff: RE: [Histonet] shelf life of working antibody solutions in IHC

Here it is

Regards,

Tony Henwood MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) (Retired)
Principal Scientist, the Children’s Hospital at Westmead (Retired)
Adjunct Fellow, School of Medicine, University of Western Sydney.

From: Gudrun Lang via Histonet<mailto:histonet at lists.utsouthwestern.edu>
Sent: Sunday, 2 July 2023 4:59 AM
To: histonet at lists.utsouthwestern.edu<mailto:histonet at lists.utsouthwestern.edu>
Subject: [Histonet] shelf life of working antibody solutions in IHC

Hi all!

I have tried to find a general instruction for the shelf life of antibody
working solutions.

With automated IHC you usually fill the container with the working solution
and depending on the frequency of usage they stay on the instrument at
roomtemperature (or higher) or are put in the fridge again.

The working solutions are up to 10 ml and may last for months. The
antibody-diluent is from the same company of the instrument. The titers are
in a range from 1:10 to 1:3000. - so a very heterogen situation.



How do you handle this? Have you a general rule, when the solution has to be
discarded? Is it just a matter of positiv-controls?



Thanks in advance

Gudrun Lang

Biomedical scientist

Austria





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