Epidermal SH-protease inhibitor in human neoplasms and their metastases.

The presence of the human epidermal SH-protease inhibitor in human tumours of different types was examined using double radial immunodiffusion against specific antisera to the inhibitor. The immunoreactive protein was found to be present in all the tumours with criteria of epidermoid carcinoma identifiable microscopically. Most small cell anaplastic, fusiform, and polygonal bronchial carcinomas were also found to contain immunoreactive protein. If the primary tumour contained the inhibitor, all metastases examined were also found to contain it. The identity of the inhibitors in epidermoid carcinomas and in epidermis was confirmed by immunoelectrophoretic and gel chromatographic methods. The results suggest that the epidermal SH-protease inhibitor is a property closely associated with squamo-epithelial tissue differentation, which also appears in neoplastic squamous epithelium.