[The change of immunocompetent cells in normal human dental pulp during development of immature permanent teeth]

To study changes of several immunocompetent cells (ICCs), namely, pulpal dendritic cells (PDCs), T lymphocytes, B lymphocytes, and endothelial cells, in normal human dental pulp according to different development stage of completely erupted but not fully developed premolar in order to provide evidence for local immune defense mechanisms during development of immature permanent teeth.

Based on the dental development status, the pulp tissue was classified into the following groups: big trumped-shaped group, small trumped-shaped group and closed group. The above mentioned cells were immunohistochemically examined by use of HLA-DR, CD45RO, CD20 mouse anti-human monoclonal antibodies. Double-staining was also done by use of the former two antibodies. The number of positively stained cells or blood vessels was counted and statistically analyzed.

1. Normal dental tissue of three groups all expressed HLA-DR+ PDCs. Among three groups, the number of HLA-DR+ cells in big trumped-shaped group was more than that of small trumped-shaped group and closed group. 2. There was no significant difference of positive blood vessel rate of HLA-DR expressing endothelial cells among three groups. 3. There was no significant difference of CD45RO+ T cells among three groups. 4. By use of double-labeling immunohistochemistry, HLA-DR+ PDCs and CD45RO+ T cells were found to be rarely in contact with each other. Correlation analysis between two kinds of cells did not indicate the linear relationship.

The number of PDCs tends to decrease with increasing age in the developing dental pulp of human normal tooth, other ICCs are not related with dental development.