PGP and eosinophilic esophagitis: Epithelial mucosa underwent immunofluorescence staining with anti-MBP and anti-VIP to detect eosinophils nearby VIP-expressing cells, anti-tryptase and anti-VIP to detect mast cells nearby VIP-expressing cells, and anti-PGP 9.5 to detect VIP being expressed by nerve cells in human EoE biopsies (Figure 4).