The response of Langerhans cells to palatal cover plates in the rat

Abstract

It is not known whether the long-term use of prosthetic or orthodontic appliances, which may be associated with fungal infections, affects Langerhans cells (LC) in the underlying mucosa. The number and distribution of LC was studied in rat palatal epithelium over a 7-day period after insertion of cover plates. Smears of cultures taken before and at the end of the experiment were examined for fungi. LC were identified in cryostat sections using an immuno-alkaline phosphatase technique to demonstrate cell surface Ia (Class II Major Histocompatibility Complex antigens). Occluding the palate predisposed to food trapping and microbial growth. Fungi were recovered from the plates of two animals but not from control or experimental animals before fitting the plates. No differences in LC numbers were found on days 1 and 3 after insertion of the plates, but a significant increase was observed on day 7. It is not known whether this change represents a true increase in LC number or an increase in Ia expression, but it is likely to be the response to an alteration in the number and/or nature of antigens penetrating the mucosa because of microbial growth and food retention.