Histochemical and Immunohistochemical Demonstration of Macrophages and Dendritic Cells in the Lingual Periodontal Ligament of Rat Incisors.

Abstract

Summary. The distribution of macrophages in the lingual periodontal ligament of rat incisors was surveyed by histochemical and immunohistochemical methods. Numerous macrophages showing intense ACPase reactions were located primarily in the shear zone of the periodontal ligament. Immunostaining with an ED1-monoclonal antibody that recognizes various subpopulations of macrophages revealed plentiful positive cells showing flamelike profiles throughout the periodontal ligament, in addition to regular macrophages associated with sinusoidal blood vessels. A similar distribution of flamelike cells expressing Ia antigens was demonstrable with immunostaining using an OX6-monoclonal antibody. A consecutive staining of sections for ACPase histochemistry followed by immunoreactions for Ia antigens revealed the presence of two types of the flamelike cells in the periodontal ligament: one with and the other without distinct ACPase activity, corresponding to the macrophage and the dendritic cell, respectively. Either type of flamelike cells was located in the bone-related and shear zones, whereas only dendritic cells without ACPase activity were restricted to the tooth-related zone. OX6-immunonegative cells showing ACPase reactions were also found in the periphery of the sinusoidal blood vessels.Our data are the first to demonstrate the abundance of macrophages and dendritic cells expressing Ia antigens throughout the lingual periodontal ligament of rat incisors. In addition to regular macrophages, an exclusive localization of macrophages with flamelike extensions has been demonstrated in the bone-related and shear zones of the ligament. The region-specific arrangement of macrophages and dendritic cells with various histochemical and immunological features suggests that the periodontal ligament of rat incisor is a useful model for analyzing the process of differentiation of antigen-presenting cells.

Epithelial Cell Rests of Malassez and OX6‐Immunopositive Cells in the Periodontal Ligament of Rat Molars: A Light and Transmission Electron Microscope Study

“…The OX6 monoclonal antibody targets MHC class II (Ia) antigen, which is present on dendritic cells (considered to be most potent APCs), some macrophages and few B-lymphocytes (McMaster and Williams, 1979;Kawahara et al, 1992;McMenamin et al, 1992). As none of the existing monoclonal antibodies are lineage specific, the MHC class II antigen expression was used in conjunction with cell morphology and ultrastructure for cell type discrimination.…”

Characteristics of resident dendritic cells in various regions of rat periodontal ligament

“…A number of studies have reported the presence of DCs including Langerhans cells in the gingiva (Gemmell et al limited (Okiji et al 1990;Kawahara et al 1992;Kan et al 2001). The PDL is a soft specialized connective tissue that forms the structural attachment between the tooth and the surrounding alveolar bone (Lekic and McCulloch 1996).…”

Increased Gene Expression of Toll-like Receptors and Antigen-Presenting Cell–related Molecules in the Onset of Experimentally Induced Furcation Lesions of Endodontic Origin in Rat Molars

“…Moreover, defense cells such as macrophages and dendritic cells (DCs) reside in the PDL, most likely to maintain local homeostasis and cope with infectious challenges (2,3). We have recently shown that resident type of DCs in the rat PDL show heterogeneity in terms of morphology and cell surface antigen expression in different regions of the PDL, probably reflecting the differences in the microenvironment, such as the amount of external antigens, in different regions (4).…”