Immunohistochemical studies of beta-hexosaminidase in neoplastic and normal tissues with monoclonal antibodies.

A total of 87 human specimens with 10 histological types of primary neoplasm were studied immunohistochemically with monoclonal antibodies specific for beta-hexosaminidase (Hex). High levels of Hex were found in malignant neoplasms of the skin, cervix, colorectum and in benign as well as neoplastic plasma cells, while no activity was detected in normal epidermis, normal colorectal epithelium or benign naevi. The strongest immunohistochemical reaction was revealed in tumor cells of malignant melanoma. Adenomas and adenocarcinomas of the colorectum showed high levels of Hex with a basal pattern of immunoreactivity more frequent in the tumor cells of adenocarcinomas than adenomas. Fibroblasts and macrophages in the tumors often disclosed immunoreactivity. In most of the sections (including those from plasma cell neoplasms), 7E4 antibody showed low immunoreactivity compared to 2E3, except for non-neoplastic plasma cells, which were as a rule positive with 7E4 and largely negative with 2E3 antibody. This result probably indicated different isoenzymes in benign and neoplastic plasma cells.