Antibody Expiration in the Context of Resource Limitation: What Is the Evidence Basis?
EC Savage, BR DeYoung. University of Iowa, Iowa City, IA
Background: The recent implementation and enforcement of CAP Survey Checklist ANP 22432 has renewed attention on the issue of outdating of antibodies for immunohistochemistry. The requirement for this position is rooted in CLIA '88 and its granting of anylate specific reagent status to primary antibodies as well as the CAP's role as laboratory accrediting agency as deemed by CMS with the primary driver likely being patient safety. However, in a time of limited resources, one questions the evidence base for this position. Two previous older studies have investigated the issue of expired antibodies, although both in a limited manner.
Design: Methods and Materials: The staining patterns of 26 recently acquired primary antibodies and their expired counterparts (ranging from 6-24 months with an average expiration interval of 13 months) were examined sequentially by two independent reviewers on formalin-fixed paraffin embedded tissue sections utilizing standard immunohistochemical technique. Both staining intensity (ranging from 1 to 3+) and percent of cells stained (I = <25%, II = 25-50%, III = 50-75%, and IV = >75%) were recorded. Positive and negative controls stained appropriately for all antibodies.
Results: Twenty of the twenty-six antibodies tested exhibited no difference in either percent positive cells or staining intensity (76.9%). Of the remaining six, three showed better performance with the expired cohort and three with non-expired antibodies. It should be noted, no antibody's staining characteristics varied by more than one step, and there were no cases where positive staining was lost secondary to antibody expiration.
Conclusions: In concordance with a small number of previous reports, there are negligible differences in immunostaining when comparing outdated antibodies to current ones. Given the current constraints on healthcare resources, efforts to procure exemption for primary antibodies from existing regulations may prove beneficial and would not adversely impact patient care assuming.
Category: Quality Assurance
Monday, March 9, 2009 1:00 PM
Poster Session II # 240, Monday Afternoon