Immunofluorescent Labeling in Nasal Mucosa Tissue Sections of Allergic Rhinitis Rats <em>via</em> Multicolor Immunoassay

Allergic rhinitis (AR) is a chronic, non-infectious inflammatory disease of the nasal mucosa, primarily mediated by specific immunoglobulin E (IgE), affecting approximately 10%-20% of the world's population. While immunofluorescence (IF) staining has long been a standard technique for detecting disease-specific protein expression, conventional IF techniques are limited in their ability to detect the expression levels of three or more proteins in the same sample. Consequently, multicolor IF techniques have been developed in recent years, which allow the simultaneous labeling of multiple targets in cells or tissues. This protocol provides a comprehensive overview of the process for establishing a rat model of AR, obtaining nasal mucosal samples, and the technical procedures for multicolor immunofluorescence. All rats in the AR group exhibited typical symptoms such as sneezing, a runny nose, and an itchy nose, with behavioral observations scoring ≥5 points. Hematoxylin and eosin (H&E) staining revealed increased inflammatory cell counts and disrupted nasal mucosal integrity in the AR group. Multicolor immunofluorescence (mIF) demonstrated increased expression of RORγt and TICAM-1, while Foxp3 expression decreased in the nasal mucosa tissue of AR rats.