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

Monoclonal antibody (G6KI2) specific for differentiated keratinocytes was developed using in vitro immunization against the SCC‐25 cell line. G6K 12 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. G6KI2 was also reactive to keratinocytes in most moderatel‐y‐ and well‐differentiated SCC tissues. Immunoelectron microscopic examination further demonstrated that the G6K. 12‐immunoreactive area was at the outer surface of the entire plasma membrane, including the microvilli of stratified SCC‐25. G6KI2‐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.