Appearance and distribution of dendritic cells and macrophages in dental pulp during early postnatal morphogenesis of mouse mandibular first molars.

Abstract

Dendritic cells and macrophages were examined in dental pulp during the postnatal development of mouse mandibular first molars, by immuno- and enzyme histochemistry. F4/80 antibody against dendritic cells and macrophages demonstrated labeled cells predominantly in and around the odontoblastic layer during tooth development from postnatal day 0 (PN0) to PN5. Labeling with Mac-1, Mac-2, and MOMA-2 antibodies against macrophages showed varied distribution patterns. Mac-1-positive cells were not detected in the dental pulp. Mac-2-positive cells appeared in the dental pulp at PN0, but not in or around the odontoblastic layer, and disappeared by PN3. A few MOMA-2-positive cells were detected in the dental pulp during the period examined. The F4/80-positive cells in and around the odontoblastic layer did not exhibit acid phosphatase or non-specific esterase activities. In addition, the F4/80-positive cells showed continued expression of Fcgamma receptor, but not class II major histocompatibility complex (MHC). Other antibodies against dendritic cells (NLDC-145, MIDC-8, and 33D1) did not label the F4/80-positive cells. We concluded that the F4/80-positive and class II MHC-negative cells in and around the odontoblastic layer may be immature dendritic cells in the early stages before eruption, weaning, and crucial exposure to antigenic stimuli. They may not only act primarily as immunosurveillance cells, but also play a role in a regulatory function and differentiation of odontoblasts.