Immunocytochemical Reactivity Comparison between Formalin-Fixed and Liquid-Based Cytology-Fixed Specimens

Area of Science:

• Cytopathology
• Immunohistochemistry
• Biomedical research

Background:

• Liquid-based cytology (LBC) offers advantages for preparing multiple specimens and performing immunocytochemistry (ICC).
• However, LBC fixing solutions can alter antigenicity and affect ICC results.
• This study investigates the impact of different LBC fixing solutions on ICC immunoreactivity.

Purpose of the Study:

• To evaluate the effect of various LBC fixing solutions on the immunoreactivity of different antigens.
• To compare ICC results from LBC-fixed samples with those from traditional 10% neutral buffered formalin (NBF)-fixed samples.

Main Methods:

• Cell line samples were prepared using four LBC fixing solutions (PreservCyt®, CytoRich™ Red, CytoRich™ Blue, TACAS™ Ruby) and NBF fixation.
• Specimens were post-fixed with NBF for ICC analysis.
• Immunocytochemical staining was performed using 24 different antibodies, and the percentage of positive cells was quantified.

Main Results:

• Immunoreactivity varied based on antigen type and fixing solution.
• Nuclear antigens showed optimal results with NBF or TACAS™ Ruby, while cytoplasmic antigens performed well or better in LBC-fixed samples.
• Significant reductions in positive cell percentages were observed for CEA, Ber-EP4, CD10, and D2-40 in specific LBC formulations compared to NBF.

Conclusions:

• ICC on NBF-post-fixed LBC cell block specimens can yield comparable immunoreactivity to NBF-fixed samples.
• The choice of LBC fixing solution influences antigen detection rates, depending on the antibody and antigen abundance.
• Careful consideration of LBC methods and antibody selection is recommended for reliable ICC results.