A MONOCLONAL-ANTIBODY KIS-1 RECOGNIZING A NEW MEMBRANE ANTIGEN ON HUMAN SQUAMOUS-CELL CARCINOMA

A KIS-1 monoclonal antibody (MAb) (IgG(1), kappa) recognizing a membra ne antigen on human squamous-cell carcinomas (SCC) was developed to un derstand their antigenicity using an esophageal SCC as an immunogen. T he KIS-1 MAb recognized a membrane antigen on a majority of esophageal , lung, and oral-cavity SCC by immunofluorescent and by immunohistoche mical analyses. In contrast, it showed little reactivity to adenocarci nomas from different organs, and none to keratinocyte cell lines. This MAb showed reactivity to the cells in the basal layer of normal esoph ageal epithelium adjacent to the esophageal SCC, but none of the other normal tissues, including esophageal epithelium far from the SCC and that from patients with non-malignant disease. The KIS-1 MAb immunopre cipitated a 46-kDa membrane protein of the esophageal SCC in nonreduci ng and in reducing conditions. It recognized the 46- and the 40-kDa pr oteins of the esophageal SCC by immunoblot analysis. These results sug gest that the KIS-1 MAb recognizes a new membrane antigen preferential ly expressed on SCC, and that this antigenicity is shared only by the cells in the basal layer of the esophageal epithelium adjacent to SCC. The KIS-1 MAb may be a new tool for understanding the antigenicity of SCC. (C) 1996 Wiley-Liss, Inc.