Consideration of visualization using the CISH (chromogenic in situ hybridization) method after HER2 FISH

Abstract

At our hospital, 2 to 4 people perform fluorescence observation to determine HER2 FISH (human epidermal growth factor receptor type 2 fluorescence in situ hybridization). However, in the case of equivocal or difficult-to-diagnose cases, observation takes a long time, and the fluorescence fades due to excitation light irradiation, making it difficult to confirm the signal under direct vision. Therefore, we investigated visualization using the CISH (chromogenic in situ hybridization) method after HER2 FISH. As a result of the study, (1) cocktail antibodies (anti-Rhodamine monoclonal antibody <×2,000>), anti-Fluorescein antibody <×200>) were incubated at room temperature for 30 minutes, (2) AP-labeled anti-IgG polyclonal antibody (Histofine Simple Stain AP <R>) was incubated at room temperature. 30 minutes, (3) BCIP/NBT 1–3 minutes at room temperature, after washing (4) PO-labeled monoclonal anti-IgG antibody (Histofine Simple Stain MAX PO <M>) 30 minutes at room temperature, (5) AEC 10 minutes at room temperature, after drying (6) Visualization became possible with the protocol of water-soluble Aquatex encapsulation. We believe it will be highly useful, including reducing problems with fading and storage space at −20°C, providing virtualization to clinicians, and using it for internal quality control and education.