TNF-alpha expression and apoptosis-regulating proteins in oral lichen planus: a comparative immunohistochemical evaluation

Apoptosis appears to be the mode of cell death by which damaged cells are r emoved from the lesional tissue in oral lichen planus (OLP). In the present study, OLP biopsies were immunohistochemically evaluated for TNF-alpha and apoptosis-regulating proteins in an attempt to compare their phenotypic ex pression. Deparaffinized tissue sections from 22 OLP and 10 control oral bi opsy specimens were immunohistochemically stained with anti-Bcl-2, anti-Bcl -x, anti-Bax and anti-TNF-alpha antibodies. Keratinocytes did not show any immunoreactivity for Bcl-2, while a uniform intense staining for this prote in was evident in the lymphocytic infiltrate of OLP specimens. Immunoreacti vity for TNF-alpha was seen in 17/22 OLP cases. All control tissues were TN F-alpha negative, thus indicating a possible involvement of this cytokine i n the pathogenesis of OLP, The differences in the staining intensities of B cl-x and Bax between OLP and normal epithelium were slight; therefore an ob vious association of the phenotypic TNF-alpha expression with these apoptos is-regulating proteins was not apparent.