Consecutive sections of sinus mucosa from a patient with allergic fungal sinusitis (EFS) top section is stained with H&E and lower one with FITC labelled major basic protein (MBP). The right hand third of the picture shows epithelium and intact eosinophils (with intact granules containing MBP). On the left hand side, clusters of eosinophils have released MBP. Low power MBP is toxic to the sinus epithelium.
Mayo Foundation 2003