IS THE CARBOHYDRATE SIALOSYL-TN A-MARKER FOR ALTERED, NONMALIGNANT ACTIVITY IN SQUAMOUS EPITHELIUM IN THE HEAD AND NECK REGION

Cell surface carbohydrates are involved in many cell functions such as cellular differentiation, adhesion, and invasion. A carbohydrate, sia losyl-Tn (STn), is expressed in many human carcinomas but generally no t in normal epithelia. In the oral mucosa, however, STn has recently b een observed on basal cells in some lesions with epithelial hyperplasi a and dysplasia. The aim of this study was to carry out a systematic i nvestigation of STn expression on epithelial basal cells in hyperplast ic, 'borderline' malignant, and malignant head and neck lesions, to se e if the expression of STn is associated specifically with hyperplasti c conditions. Using the primary monoclonal antibody TKH2, normal contr ols did not reveal STn. STn was detected on probably post-mitotic basa l cells in hyperplastic head and neck lesions and on basal cells adjac ent to cancers, but not within the carcinomas. A Ki67 antibody reacted with basal cells in other locations. The most highly differentiated l esions, such as focal epithelial hyperplasia and verrucous hyperplasia , revealed a high percentage (86 per cent in both cases) of STn reacti vity. The least-differentiated verrucous carcinomas (VCs) and keratoac anthomas (KAs) did not express STn, in contrast to the highly differen tiated VCs and KAs. These findings indicate that STn-negative cases ma y have a greater malignant potential that the STn-positive cases. In c onclusion, STn expressed on basal cells is possibly a marker for non-m alignant conditions with altered basal cell activity and for highly di fferentiated verrucous carcinomas.