TUMOR-ASSOCIATED GLYCOPROTEIN EXPRESSION IN SALIVARY-GLAND MUCOEPIDERMOID CARCINOMAS - AN IMMUNOHISTOCHEMICAL STUDY USING THE MONOCLONAL-ANTIBODY B72.3

The monoclonal antibody B72.3 recognizes a mucin-like glycoprotein whi ch is expressed in a variety of human malignancies including adenocarc inomas of the breast, colon, lung, endometrium, pancreas, and ovary. T he antibody, an immunoglobulin G (IgG1) subclass monoclonal antibody, was generated from membrane enriched fractions of metastatic mammary c arcinoma. Because the antigen detected by B72.3 is expressed in a broa d spectrum of human neoplasms, B72.3 is a potentially useful marker fo r glandular neoplasms. Despite its potential usefulness, there is only one previous comprehensive study which has examined the distribution of the tumor-associated glycoprotein (TAG-72), as detected by B72.3, i n salivary neoplasms. We examined 21 mucoepidermoid carcinomas with th e antibody. Twenty (95%) of the 21 carcinomas stained positively. The only carcinoma that did not stain was initially thought to be a high-g rade mucoepidermoid carcinoma based on immunohistochemical staining. F urther review, however, indicated that this lesion was most likely a p ure squamous cell carcinoma, and the absence of TAG-72 antigen express ion was helpful in this regard. Among those neoplasms which stained wi th B72.3, the strongest staining was seen in the low grade carcinomas. These results suggest that B72.3 may be a useful marker for glandular differentiation in mucoepidermoid carcinomas.