Methods of cytologic smear preparation and fixation - Effect on the immunoreactivity of commonly used anticytokeratin antibody AE1/AE3

OBJECTIVE: To evaluate the effect of fixation and methods of cytologic smea r preparation on the immunoreactivity of commonly used anticytokeratin anti body AE1/AE3. STUDY DESIGN: Scrape cytology smears and formalin-fixed, paraffin-embedded tissue sections (FPTS) of 20 unfixed, fresh specimens submitted for intraop erative consultation were studied by the immunoperoxidase method. In additi on to the morphologic examination, the smears and FPTS were evaluated for i ntensity and proportion scores. For each specimen, two scrape cytology. sme ars were wet fixed in 95% ethanol, and 12 smears were air dried without fix ation. Air-dried smears were ei-ther postfixed after rehydration in saline or fixed directly without rehydration by one of the three fixatives: alcoho lic formalin, 95% ethanol with 5% acetic acid or 95% ethanol. RESULTS: Both intensify and proportion scores were higher with rehydrated, air-dried smears as compared to those without rehydration and were comparab le to those with wet-fixed smears and FPTS. In the rehydrated group, the op timum results were achieved when the smears were postfixed with alcoholic f ormalin. CONCLUSION: The method of preparation and fixation had variable effects on the immunoreactivity of anticytokeratin antibody AE1/AE3. The optimum resul ts were achieved with saline-rehydrated, air-dried smears post-fixed in alc oholic formalin. To evaluate the role of intersample variation, further, la rger studies are recommended on this and other antibodies before appying th em to different types of cytologic smears.