Abstract:
Oral lichen planus (OLP) is a chronic inflammatory mucosal disease of unknown
cause, however many studies have supported the immunopathogenesis of OLP.
Because Langerhans cells (LCs) is an essential cell in the processing of antigen and
promulgation of the immune response in skin and mucosa, they may be important in
OLP. The purpose of this study was to determine number of S-100 positive LCs in
OLP.
Polyclonal antibody reacting with LCs was used to characterize the expression of
S-100 proteins in OLP compared with the adjacent tissues, fibroma and normal
epithelium by using immunohistochemical technique. The specimens were fixed in
formalin and embedded in paraffin. S-100 positive LCs should be considered as LCs
when fulfilling 2 criterias : 1) the whole cell body being visible ; 2) with at least one
dendritic process. Graticular outlining an area of 0.064 mm2 was used at
magnification of 400x to assist in counting cells in stained sections. The grid was
positioned parallel to the epithelial-connective tissue interface. Counts from 3
adjacent high power fields in a single section were averaged. Differences in cell
counts between OLP and unaffected adjacent tissues were statistically evaluated using
Wilcoxon Matched-Pairs Signed-Ranks test. Whereas the differences in cell counts
between OLP and fibroma ; OLP and normal epithelium, were statistically evaluated
using Mann Whitney U-Wilcoxon Rank Sum W test.
The results demonstrated that the number of stained LCs in OLP were
significantly much more prominent than in unaffected-adjacent tissues, fibroma and
normal epithelium (p<0.05), and the number of stained LCs in unaffected adjacent
tissues were significantly more than in normal epithelium (p<0.05). It suggested that
significantly increased LCs might play a role in pathogenesis of OLP or represent an
event secondary to the pathologic changes in the disease