Significance of liquefaction degeneration in oral lichen planus: a study of its relationship with apoptosis and cell cycle arrest markers

Objective. To assess the utility of liquefaction degeneration as a marker of apoptosis in oral lichen planus (OLP). Methods. TdT-mediated dUTP-biotin nick-end labelling (TUNEL) assay and immunohistochemical methods were used to detect p21 proteins and the active form of caspase 3 in 32 tissue samples of oral mucosa with OLP and 20 samples of normal oral mucosa. Results Liquefaction degeneration was moderate or intense in 27.5% (n = 8) and slight in 72.4% (n = 21) of OLP samples. There was low expression of apoptosis markers (TUNEL, active caspase 3 form), which was not significantly associated with liquefaction degeneration of the basal cell layer. Basal and suprabasal expression of p21 was significantly more frequent in samples with more intense liquefaction degeneration of basal cells (P < 0.01). Conclusions. Our results demonstrate that liquefaction degeneration, as a morphological expression of T lymphocyte attack, does not unequivocally indicate apoptosis. Attacked basal cells more frequently respond with cell-cycle arrest or senescence than with apoptosis.