Exudation into the nasal cavity of carbon particles injected into nasal polyps

A colloidal carbon solution was prepared by dissolving 50 mg of ultra fine carbon particles (diameter: 21-50 nm) and polyvinylpyrrolidone-- for stabilizing the dispersion--in 1 ml physiological saline, and injected into the nasal polyps of allergic patients. Two hours after injection, the nasal polyps were removed and examined by transmission electron microscopy. Notably, carbon particles could not pass through the epithelial basement membrane and were therefore not observed between the epithelial cells, where no inflammatory cells infiltrated the epithelial layer. However, they passed through the fissure in the basement membrane, which was formed by the penetration of inflammatory cells (eosinophils) into the epithelial layer. Many carbon particles were observed in the interstitial space of the epithelial layer, where a large number of inflammatory cells accumulated. Furthermore, they passed into the nasal cavity along with the interstitial mucous fluid through the opened epithelial junction. A wide pathway from the submucosa to the nasal cavity, through which large-sized particles can pass, was demonstrated in the polyp's mucosa. Moreover, as carbon particles exhibit no chemotaxis, they must move according to the interstitial fluid flow, which suggests that the interstitial fluid flows outwardly from the mucosa during allergy.