Potential for false-positive staining with a rabbit monoclonal antibody to progesterone receptor (SP2): Findings of the UK national external quality assessment scheme for immunocytochemistry and FISH highlight the need for correct validation of antibodies on introduction to the laboratory

Merdol Ibrahim, Andrew Dodson, Sarah Barnett, David Fish, Bharat Jasani, Keith Miller

Research output: Contribution to journalArticle

33 Citations (Scopus)


This study focused on recent assessment results from the United Kingdom National External Quality Assessment Scheme for Immunocytochemistry and Fluorescence In-Situ Hybridisation breast hormone receptor module in which participants were asked to demonstrate progesterone receptors (PRs). The slides consisted of 3 infiltrating ductal breast carcinomas, previously classified as a high PR expresser, a moderate to low PR expresser, and a negative tumor. During this assessment, 2 commercial rabbit monoclonal antibodies, SP2 (Lab Vision/NeoMarkers, Fremont, CA), and 1E2 (Ventana, Tucson, AZ) were used by 15% of the participants. The SP2 rabbit monoclonal antibody showed false-positive and nonspecific staining on the previously established PR- tumor. This article highlights the necessity for all clinical laboratories to validate immunohistochemical methods and protocols when using newly marketed antibodies such as SP2; use composite tissue blocks with known levels of tumor expression such as a high, mid, and negative expression; and participate in internal and external quality assessment schemes, which can highlight potential technical issues in laboratory methods.

Original languageEnglish
Pages (from-to)398-409
Number of pages12
JournalAmerican Journal of Clinical Pathology
Issue number3
Publication statusPublished - Mar 1 2008



  • Antibody validation
  • Breast hormonal receptors
  • Progesterone receptor
  • Quality assurance
  • Rabbit monoclonal antibody
  • SP2

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this