Antibody Expiration in the Context of Resource Limitation

Abstract

The implementation and enforcement of the College of American Pathologists Survey Checklist ANP 22432 has renewed attention on the issue of outdating of antibodies used for immunohistochemical analysis. The current study examined the staining patterns of 26 recently acquired primary antibodies and their expired counterparts. Two reviewers examined sequential sections of formalin-fixed, paraffin-embedded tissue samples for staining intensity and percentage of positivity. Appropriate positive and negative control studies were performed. Of the 26 antibodies, 20 exhibited no difference in percentage of positivity or staining intensity. Of the remaining 6, 3 showed better performance with the expired cohort and 3 with nonexpired antibodies. However, no antibody staining characteristics varied by more than 1 step, and in no case was positive staining lost after antibody expiration. Negligible differences exist in immunostaining between outdated and current antibodies. Thus, exemption for primary antibodies from existing regulations would conserve resources without adversely impacting patient care.

Antibodies are forever: a study using 12–26‐year‐old expired antibodies

“…This was expected, given the fact that we measured the whole sample, fetal calf serum, or other proteins included. Similarly, blinded pathologists could not reliably identify stains with aged reagents, as shown previously by Savage et al . (not shown).…”

“…Monoclonal antibodies are produced by unique hybridomas, which themselves can be subcloned, may switch isotype, or may change in performance over the years; these are all factors whose control is covered by commercial confidentiality. Unlike previous experiments, in which the period after the expiry date was mostly limited to a few months or years, in the current study there was a chance that because of the very long time intervals the expired reagents, both monoclonal and polyclonal, would be entirely different from, but with the same declared specificity as, the current ones.…”

“…Finally, serial sections stained with new and expired antibodies, matched for clone and/or format, were shown blind to several pathologists, and correct identification of the antibody source was scored . Immunohistochemistry not being ideal for in‐situ antigen quantitative methods, and because of the considerations above, we did not use image analysis.…”

“…The expiry limit of commercially produced antibodies is defined by multiple parameters associated with the intended use . Mandatory disposal of expired lots has a cost for health systems and has raised concerns, particularly because recently expired IHC antibodies have been shown to perform identically to fresh batches …”

“…A few well‐planned studies have investigated the shelf‐life of primary diagnostic antibodies for immunopathology . However, most of the reagents tested expired 12–32 months before evaluation, with a handful being tested and found to be effective 77 months and 134 months after the expiry date.…”