Dendritic cells and macrophages expressing class II antigens in the normal rat incisor pulp.

This study has identified and characterized class II (Ia) antigen-expressing cells in the normal rat incisor pulp by immunohistochemistry and flow cytometry. Two types of Ia-expressing cells occurred: one with a pronounced dendritic appearance located primarily in the periphery of the pulp, and one with morphological characteristics similar to those of macrophages. The latter cells were mainly observed in the central portion of the pulp. A numerical ratio of 1:4 was established between the two cell types. The existence of Ia-expressing cells suggests an inherent capacity of the pulp to process and present foreign antigens.