[A monoclonal antibody reactive with human squamous cell carcinoma of the esophagus]

Monoclonal antibody KYSM-1, whose immunoglobulin was IgM, was produced against human esophageal squamous cell carcinoma (KE-1) which has been maintained by serial subcutaneous transplantation in nude mice. In immunohistochemical reactions with various cancer tissues, KYSM-1 showed a strong reaction specific to squamous cell carcinomas of the esophagus, oral cavity and lung (92%, 95/103 and 100%, 3/3 and 100%, 7/7), with the lack of gastrointestinal adenocarcinomas and pulmonary nonsquamous cell carcinomas (small cell and large cell carcinomas). In contrast to this result, no reaction was recognized in several normal tissues, such as the lung, stomach, colon, liver, spleen, lymph node, pancreas, kidney, and mammary gland, however, a weak reaction was found in the basal layer of the esophageal mucosa. Antigenetic determinant of squamous cell carcinoma reactive with KYSM-1 was revealed to be protein moiety after enzyme treatment, and molecular weight of the antigen was about 60,000 analysed by Western blotting. These results suggest that KYSM-1 may be useful for not only immunoscintigraphy but also for the targeting chemotherapy.