Expression of macrophage inflammatory protein 3alpha in human inflamed dental pulp tissue.

Severe pulpitis resulting from dental caries is characterized by marked inflammatory infiltrate such as lymphocytes. Little is known about the recruitment of these cells into the dental pulp lesions of carious teeth. Macrophage inflammatory protein-3alpha (MIP-3alpha), a CC chemokine attracts CC chemokine receptor 6 (CCR6)-expressing T cells. We examined the distribution of MIP-3alpha-positive and/or CCR6-positive cells in human inflamed and normal dental pulp by immunohistochemistry. MIP-3alpha was observed in all inflamed pulp sections, and was mostly distributed in macrophages that had accumulated in the area adjacent to carious lesions. Furthermore, CCR6 expression was also observed in the infiltrating lymphocytes. In contrast, MIP-3alpha and CCR6 were rarely detected in normal pulp. These findings suggest that MIP-3alpha plays a role in the advancement of pulpal inflammation via the recruitment of CCR6-expressing lymphocytes.