[How Long Are Unstained Sections Available for Immunostaining? -A Study of Antigenicity Preservation Time-].

It is well known that the antigenicity of unstained sections put on a slide glass decreases when the slides are stored at room temperature. Several methods have been reported to prevent reduced antigenicity, such as storing in a dark place at 4°C, covering sections with paraffin or a sheet, and storing in a deep freezer at -80°C. The aim of the present study is to determine how long unstained sections can be stored in a refriger- ator (ie, 1 week, 2 weeks, 1 month and 2 months). Each section was well stained and equal to the day 0 section for CD3, CD20, bcl-2, bcl-6, ER, PgR, HER2, Ki-67, chromogranin-A, synaptophysin, CK5, CK7, CK20, and TTF-1. In conclusion, unstained sections can be used for immunostaining after at least 2 months of storage, and preparing several control sections and storing them in a refrigerator is useful for minimizing control block loss. [Original].