Perforin and granzyme B involvement in oral lesions of lichen planus and chronic GVHD.

BACKGROUND

Oral lesions of lichen planus and chronic graft-vs.-host disease (cGVHD) have similar clinical and histological features, but distinct etiology. Apoptosis induced by cytotoxic T lymphocyte has been proposed as a mechanism of keratinocytes death. Cytotoxicity can be mediated by granules containing granzyme B and perforin. Since common features can reflect similarities in immunological mechanisms, we studied the role of those molecules in both diseases.

METHODS

We analyzed 29 cases of oral lichen planus and 27 of oral cGVHD. The sections were studied on H&E, perforin and granzyme B staining.

RESULTS

The total means (epithelium plus connective tissue number) of the granzyme B- and perforin-positive cells were significantly higher in cGVHD than in oral lichen planus lesions (P<0.05). Also, it was found that the higher the number of perforin+ cells, the higher the number of granzyme-B+ cells in the epithelium and in the connective tissue for both groups (P < 0.05). In oral lichen planus, the number of single apoptotic bodies had a positive correlation with connective tissue granzyme immunostaining and a negative correlation with perforin (P<0.01). On the contrary, in oral cGVHD, the number of apoptotic body clusters presented a positive correlation with connective tissue perforin (P<0.01).

CONCLUSIONS

Our findings indicate that apoptosis in oral lichen planus seems to be correlated with granzyme B release, while in oral cGVHD, perforin seems to be more important. Although these diseases present clinical and histological similarities, subtle differences seem to exist in their pathogenetic mechanisms.