Immunohistochemical Detection of FOXO3a Protein Expression in the Lungs

An immunohistochemical assay was performed with a FOXO3a polyclonal primary antibody (LSBio, Seattle, WA), an HRP goat anti-rabbit IgG secondary antibody and a DAB color reagent kit (ZSGB-BIO, Beijing, China). A FOXO3a immunohistochemical assay was performed on lung tissue according to a standard procedure. Under the microscope, a brownish-yellow color was observed on the sites with positive expression of FOXO3a. Image-Pro Plus 6.0 image analysis software was used to determine the average optical density (AOD) of FOXO3a-positive cells, and the AOD value represents the protein expression of FOXO3a. A total of 10 fields of view were randomly selected and assessed. Their average value was used as the representative value of the section.