Alterations in PNA binding of keratinocytes in oral keratosis.

Changes in the expression of peanut lectin (PNA) were examined in keratinocytes of oral keratosis showing a mixture of hyperortho- and hyperparakeratinized epithelium. In the hyperorthokeratinized epithelium, which was reacted with anti-filaggrin antibody in both granular and cornified cells, PNA bound to the surface of keratinocytes from the spinous layer to the granular layer. Neither anti-filaggrin nor PNA reactions were detected in keratinocytes of the hyperparakeratinized epithelium. After neuraminidase pretreatment, however, PNA staining appeared in all cells, except cornified cells, of both hyperortho- and hyperparakeratinized epithelia. These findings suggest that PNA-binding epitopes in keratinocytes were modified by sialic acid during the hyperparakeratotic process of oral keratosis.