MAST CELL AND EOSINOPHIL DISTRIBUTIONS IN NASAL INVERTED PAPILLOMA

Abstract

An increased number of mast cells and eosinophils can be recognized in the epithelial layer of nasal mucosa from allergic subjects; these cells are known to play an important role in the manifestation of nasal allergy. Eosinophils accumulate under the effect of eosinophil chemotactic factor released by mast cells. However, the mechanism of accumulation of mast cells has not yet been clarified.
Our previous studies have shown that colony stimulating activity of the basophil/eosinophil lineage is enhanced under proliferative conditions for nasal epithelial cells. We therefore studied the distribution of mast cells and eosinophils in inverted papilloma of the nose, in which we can identify proliferation of nasal epithelial cells.
Nasal inverted papilloma from 5 patients were examined for mast cell and eosinophil distributions. Serial staining of nasal inverted papilloma showed that the number of mast cells and the percentage of formalin sensitive mast cells within 50μm of the tumor site and 50μm above the basement membrane were 16576±5729/mm³ (90.8%) and 4697±304/mm³ (76.1%), respectively. However, in comparison with the tumor site, significant differences in the distribution and number of mast cells were seen in the stromal area. The number of mast cells and the percentage of formalin sensitive mast cells within 50μm and 50μm above the basement membrane were 2880±238/mm³ (0%) and 3096±152/mm³ (0%), respectively. Furthermore, the number of mast cells in the tumor site was significantly higher than that of mast cells in the epithelial layer of the inferior nasal turbinate and paranasal sinus membrane taken from patients with chronic sinusitis. On the other hand, many eosinophils had also accumulated in the nasal inverted papilloma, but there was no difference in the distribution of eosinophils in comparison to the tumor site and the stromal area.
The findings demonstrate differences between the stromal area and the tumor in terms of the phenotype and the number of mast cells; these are postulated to be due to distinct microenvironmental factors that affect mast cells at these sites.