Monoclonal antibody G6K12 specific for membrane-associated differentiation marker of human stratified squamous epithelia and squamous cell carcinoma

Abstract
Monoclonal antibody (G6K12) specific for differentiated keratinocytes was developed using in vitro immunization against the SCC-25 cell line. G6K12 only recognized stratified portions of cultured SCC-25 cells. Immunohistochemical examination using normal human oral mucosa showed that specific G6K12-reactivity was limited to the lower spinous-cell layers, while this antibody weakly bound to cells in basal-cell layers as well as in the upper spinous, granular and cornified-cell layers. G6K12 was also reactive to keratinocytes in most moderately- and well-differentiated SCC tissues. Immunoelectron microscopic examination further demonstrated that the G6K12-immunoreactive area was at the outer surface of the entire plasma membrane, including the microvilli of stratified SCC-25. G6K12-binding was reduced 50% by the treatment of native cells with glycoendoceramidase for 2 h. These results suggest that G6K12 recognizes a plasma membrane-anchored glycoconjugate which is specific for differentiated keratinocytes.