A Comparative Study to Determine the Most Suitable Fixative for Immunocytochemical Staining of Cytospin Slides

Park, Sang Hyuk; Chi, Hyun Sook; Won, Dahae; Cho, Young Uk; Jang, Seongsoo; Park, Chan Jeoung

Abstract

BACKGROUND
Fixation of cells is a critical procedure that can determine the success of immunocytochemical staining (ICC) of cytospin slides. In this study, we evaluated the efficacy of a number of fixatives to determine the ideal fixative for ICC of cytospin slides.
METHODS
Sixteen patients with metastatic neoplasm in the body cavity were enrolled. Cytospin slides were prepared from each patient using 5 different fixatives (cold acetone, 95% ethanol, 1:1 methanol:ethanol, 3.7% formalin, and 3:1 methanol:acetone), and the suitability of each for use with Wright's stain was compared. For 4 of the samples, appropriate ICCs were performed using all 5 fixatives and the results were compared, while for 11 samples, only the first 3 fixatives were used for ICC.
RESULTS
Using Wright stain, cold acetone, 95% ethanol, and 1:1 methanol:ethanol fixatives all showed similar efficacy when compared to the conventional methanol fixation method. However, the stain quality using 3.7% formalin or 3:1 methanol:acetone fixatives was poor due to deterioration of cell adhesion and distortion of cell morphology. Using ICC, cold acetone fixative showed stronger and more tumor-specific stainability than the 95% ethanol (decreased stainability in 6 stained slides, false positive staining of histiocytes/neutrophils in 4 stained slides, no staining of CD3 and terminal deoxynucleotidyl transferase [TdT]) and 1:1 methanol:ethanol fixatives (decreased stainability in 3 stained slides, false positive staining of histiocytes/neutrophils in 2 stained slides, no staining of CD3 and TdT).
CONCLUSIONS
Cold acetone fixative was the most efficacious among the 5 fixatives tested in this study; therefore, it is the most appropriate fixative in the preparation of cytospin slides for ICC.