MONOCLONAL-ANTIBODY G6K12 SPECIFIC FOR MEMBRANE-ASSOCIATED DIFFERENTIATION MARKER OF HUMAN STRATIFIED SQUAMOUS EPITHELIA AND SQUAMOUS-CELL CARCINOMA

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 l ayers, while this antibody weakly bound to cells in basal-cell layers as well as in the upper spinous, granular and cornified-cell layers. G 6K12 was also reactive to keratinocytes in most moderately- and well-d ifferentiated SCC tissues. Immunoelectron microscopic examination furt her demonstrated that the G6K12-immunoreactive area was at the outer s urface of the entire plasma membrane, including the microvilli of stra tified SCC-25. G6K12-binding was reduced 50% by the treatment of nativ e cells with glycoendoceramidase for 2 h. These results suggest that G 6K12 recognizes a plasma membrane-anchored glycoconjugate which is spe cific for differentiated keratinocytes.