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

Abstract

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.