Extensive interstitial collagen deposition on the basement membrane zone in allergic nasal mucosa

To clarify whether tissue remodelling of the nasal mucosa is caused by allergic inflammation or not, we studied the amount and distribution of collagen in human nasal mucosa of 13 perennial allergic patients and 13 non-allergic subjects. The total amount of collagen and other proteins in nasal mucosa was determined by absorbency at 540 nm and 605 nm of a solution eluted from tissue sections stained with sirius red and fast green. Distribution of collagen type I, III and IV was observed by immunohistochemistry. The thickness of the basement membrane zone underlying epithelia was histologically estimated. Results were as follows: i) There was no significant difference in the total amount of collagen between allergic and non-allergic subjects. ii) Although there was no obvious change in localization of the three types of collagen, extensive immunoreactivity for types I and III collagen was observed at subepithelial basement membrane zone in allergic subjects. iii) The thickness of the basement membrane zone, which corresponds to regions positive for types I and III collagen antibodies, was statistically significantly greater in allergic subjects than in non-allergic ones. We thus concluded that tissue remodelling occurs in the allergic nasal mucosa, and that it is especially obvious in the basement membrane zone.