Neuro-immune connection in deseased dental pulp-an immunohistochemical study

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This sutdy focused on peptidergic nerve fibers and class II major histocompatibility compolex (MHC) antigen-expresing cells of the dental pulp and examined whether there are some spatial relationships in the arrangement of these structures under physiological and pathological conditions. Effects of neuropeptides on functional properties of pulpally-derived class II MHC antigen-expressing cells were also analyzed in vitro. The results obtained were as follows :1. Immunohistochemistrty and confocal laser scanninb microscopy revealed that class II MHC antigen-expressing cells of the normal humah and rat dental pulp are frequently distributed in close proximity to blood vessels and nerve fibers.2. In human teeth bearing dentinal caries and rat molars subjected to experimental caries induction, a localized accumulation of class II MHC antigen-expressing cells was markedly observed along the pulp-dentin border subjacent to the pulpal end of the dentinal tubules communicating with the carious lesion. A further analysis on the human carious teeth demonstrated that neuropeptide-containing nerve fibers extensively sprouted and thus markedly increased their density in the area where the accumulation of class II MHC antigen-expressing cells was evident.3. Substance P stimulated, but CGRP inhibited the proliferation of mitogenstimulated T lymphocytes when class II MHC antigen-expressing cells isolated from rat pulps were used as accessory cells.These findings suggest that sensory nerve fibers of the dental pulp influence upon the function of class II NHC antigen-expressing cells through release of neuropeptides from nerve endings. Such a neuro-immune interaction may play a part in the initiation of the immunodefense of the dental pulp.