title: The effect of the small amount of formaldehyde in the SurePath liquid when establishing protocols for immunocytochemistry.
abstract: BACKGROUND
  SurePath®is an ethanol-based liquid fixative. In addition to ethanol, it also contains a small amount of formaldehyde (<0.2%). The aim of this study was to investigate the immunoreactivity of cells stored for different lengths of time in the SurePath liquid.
  
  
  METHODS
  Rest material from one malignant and three benign effusions were fixed in SurePath for 1-12 days. Cytospins were incubated with cytokeratin 7 antibody (AB) to evaluate the staining intensity of carcinoma cells and benign, reactive mesothelial cells. Protocols varied as to pretreatment and AB incubation time.
  
  
  RESULTS
  Reduced immunostaining intensity was seen within 5 days of storage in the SurePath liquid. It was restored when the pretreatment time was prolonged.
  
  
  CONCLUSIONS
  The small amount of formaldehyde in the SurePath liquid seems to affect the immunoreactivity. Local immunocytochemistry protocols in the cytology laboratories should consider this when optimizing their procedures. Postfixation with formalin should be omitted.
authors.affiliation: Address: Section Biomedical Education, Høgskolen i Oslo og Akershus, Oslo, Norway.
authors.forename: Ellen Cathrine
authors.initials: EC
authors.lastname: Bjønness-Jacobsen
authors.affiliation: Address: Section Biomedical Education, Høgskolen i Oslo og Akershus, Oslo, Norway.
authors.forename: Anne Kristine Kallevåg
authors.initials: AK
authors.lastname: Eriksen
authors.affiliation: Address: Section Biomedical Education, Høgskolen i Oslo og Akershus, Oslo, Norway.
authors.forename: Vidar Nyløkken
authors.initials: VN
authors.lastname: Hagen
authors.affiliation: Address: Section Biomedical Education, Høgskolen i Oslo og Akershus, Oslo, Norway.
authors.forename: Kirsten Margrethe
authors.initials: KM
authors.lastname: Østbye
authors.affiliation: Department of Pathology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: Anna
authors.initials: A
authors.lastname: Wittersø
authors.affiliation: Department of Pathology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: Mette Kristin
authors.initials: MK
authors.lastname: Pedersen
authors.affiliation: Department of Pathology, Akershus University Hospital, Lørenskog, Norway; Campus Ahus Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: Torill
authors.initials: T
authors.lastname: Sauer
keywords: Formaldehyde effect; SurePath; immunocytochemistry