IMMUNOLOCALIZATION OF ALPHA(2), ALPHA(5), AND ALPHA(6) INTEGRIN SUBUNITS IN SALIVARY TISSUE AND ADENOMAS OF THE PAROTID-GLAND

The localization of the integrin subunits alpha(2), alpha(5), alpha(6) was studied immunohistochemically in samples of normal salivary gland and in a series of 8 pleomorphic adenomas, 5 Warthin's tumors, and 2 basal cell adenomas. In normal salivary tissue, acinar and ductal cell s expressed alpha(2) and alpha(6) chains at the basal cell pole facing the basement membrane. alpha(2) also localized at sites of cell-cell contact. No staining of the epithelial component was seen with alpha(5 ). The polarized expression of alpha(2) and alpha(6) subunits was reta ined in salivary adenomas. These subunits were present at the basal ce ll pole of solid nests, tubules and ducts of pleomorphic adenomas, as well as of the basal layer of the epithelium of Warthin's tumor, and o f the trabecular structures of basal cell adenomas. The alpha(5) subun it was consistently expressed only by cells embedded in the myxoid or chondroid matrix of pleomorphic adenomas. We conclude that the pattern of a integrin subunit expression in salivary adenomas may be related to the ''epithelial'' or ''mesenchymal'' phenotype of the neoplastic c ells.