N. Yoshiba et al., IMMUNOHISTOCHEMICAL LOCALIZATIONS OF CLASS-II ANTIGENS AND NERVE-FIBERS IN HUMAN CARIOUS TEETH - HLA-DR IMMUNOREACTIVITY IN SCHWANN-CELLS, Archives of histology and cytology, 61(4), 1998, pp. 343-352
Nerve fibers and class II major histocompatibility complex (MHC) antig
en-expressing dendritic cells have been known to gather in the dental
pulp beneath carious lesions. Significant functional interactions pres
umably occur between the neural and immune elements. The present study
analyzed the morphological relationship between class II-expressing c
ells and nerve fibers in fuman carious teeth, visualized by a HLA-DR m
onoclonal antibody and a protein gene product 9.5 (PGP 9.5) polyclonal
antibody; a confocal laser scanning microscope (CLSM) and an electron
microscope were used. In pulps affected by early caries, HLA-DR-posit
ive dendritic cells aggregated mainly in the cell-free zone associated
with bundles of PGP 9.5-immunoreactive nerve fibers, In pulps affecte
d by advanced caries, the accumulated HLA-DR-positive cells and PGP 9.
5-immunoreactive nerve fibers showed close association with each other
especially beneath the odontoblast layer: the cells even embraced the
nerve fibers. Intriguingly, class II molecules were recognized not on
ly in dendritic cells but also in the Schwann cells of non-myelinated
nerves in the pulp. Using immunoelectron microscopy, class II molecule
s were localized on the surface of the non-myelinating Schwann cells a
nd also within some vesicles, whereas myelinating Schwann cells lacked
this immunoreactivity. PGP 9.5-immunoreactive nerve fibers were also
observed densely in the odontoblast layer, and CLSM revealed an intima
te association of the nerve fibers and dendritic cells. The immunoreac
tivity for HLA-DR in Schwann cells depended upon the severity of the c
arious lesion. Class II-expressing Schwann cells are suggested to func
tion as antigen-presenting cells in addition to dendritic cells.