Monoclonal antibody 1BE12 immunoreactivity with human endometrium. Correlations with hormone receptors and...

The monoclonal antibody (MAb) 1BE12 has recently been reported to react with several human normal and abnormal tissues. In human endometrium, it reacts more strongly with carcinomas than with normal tissue. To investigate the effectiveness of MAb 1BE12 in identifying cell proliferation in human endometrial cancers, 1BE12 immunocytochemical assays (ICAs) were performed on frozen (n = 47) and paraffin (n = 100) sections with subsequent computer-assisted microcytophotometric (SAMBA) evaluation of immunoprecipitate distribution. MAb 1BE12 immunoreactivity was not impaired by tissue fixation and paraffin embedding. It reacted with normal proliferative endometrium but not with normal secretory endometrium, and immunoreactivity increased with the degree of cell proliferation and malignancy, the amount of immunostaining being greater in invasive carcinomas than in normal proliferative endometrium and endometrial hyperplasia. ICAs showed no correlation between MAb 1BE12 immunoreactivity and estrogen and progesterone receptor antigenic sites. On the other hand, MAb 1BE12 staining in frozen sections increased with Ki67, EGFR, pHER-2/neu, and cathepsin immunostaining. These findings suggest that ICAs on frozen and paraffin-embedded biopsy specimens using MAb 1BE12 along with other markers can be useful for early detection and grading of endometrial carcinoma. The relevance of MAb 1BE12 to the selection of patients for laser ablation of the endometrium rather than hysterectomy is also discussed.