Immunocytochemical Study on Distribution and Morphology of Dendritic Cells in the Tongue during Development and Growth of the Rat

Yoo, Ki Soo; Kim, Chul Hong; Kim, Woo Kap

Abstract

Activation of T cells for an immune response requires the participation of antigen presenting cells (APC) that express class II major histocompatibility complex gene products on their surface. Until recently, the macrophages have been considered to be the prime candidates for this role, but it is now recognized that other cells, including dendritic cells, B cells, activated T cells and endothelial cells, can present antigen effectively. Particularly, among them, dendritic cells (DC) are considered to be very efficient APC for various T -cell dependent immune responses in comparison with other types of APC. Nonlymphoid dendritic cells including Langerhans cells and interstitial dendritic cells strongly express the MHC class II products and have characteristic dendritic morphology. As far as we know, there is no study on the ontogeny of MHC class II -immunoreactive dendritic cells in the rat tongue. The aim of the present study is to investigate the ontogeny and morphological characterization of dendritic cells in the tongue of growing and developing rats. The distribution and morphology of the dendritic cells in the rat tongue were studied from the fetal 15 -day until 180 days after birth by means of immunocytochemical methods using anti -rat MHC class II monoclonal antibodies. The results were as follows: 1. MHC class II -immunoreactive dendritic cells were first found in the muscle layer of 17 -day fetus, and in the epithelium and lamina propria of the tongue at birth. 2. The number of MHC class II -immunoreactive dendritic cells was gradually increased with age, particularly, in the epithelium at 14th day, in the lamina propria at 14th day, and in the muscle layer at 21st day after birth. 3. Numbers of MHC class II -immunoreactive dendritic cells were higher in the dorsal part than in ventral part of the tongue at all developmental stages. Especially, dendritic cells were twice higher numbers in the epithelium, a little higher numbers in the lamina propria and almost same numbers in the muscle layer. 4. With age, shapes of MHC class II -immunoreactive dendritic cells were changed from round to dendritic and aggregated together. In conclusion, the above results suggest that the increases of the number and the changes of the morphology in MHC class II -immunoreactive dendritic cells, with age may influence on effects of cell -mediated immune responses.