Dentistry in Japan 1997 33:8-14
Second Department of Oral Anatomy, Niigata University School of Dentistry, Japan.
The distribution and cytochemical characterization of macrophages and dendritic cells were investigated in the rat lower incisor pulp, by means of acid phosphatase (ACPase) histochemistry and immunocytochemistry using an OX6-monoclonal antibody against class II MHC molecules at the light and electron microscopic levels. Histochemical staining for ACPase demonstrated the presence of intensely ACPase reactive cells containing multivesicular bodies in the central portion of the dental pulp. The cells associated with the fenestrated capillaries in the odontoblast layer showed cytological features similar to the macrophages, but much weaker ACPase reactions. A double staining for OX6-immunohistochemistry and ACPase enzyme histochemistry revealed only weak ACPase reactions in the OX6-immunopositive cells containing multivesicular bodies at both the peripheral and central portions of the pulp tissue. The results suggest that most, if not all, of the OX6-immunopositive cells situated deep in the odontoblast layer are dendritic cells having an antigen-presenting function but without phagocytic activity. An increasing number of ACPase reactive cells near the incisal end of the pulp appear to be macrophages involved in the elimination of degenerated odontoblasts.