A monoclonal antibody to a cell surface determinant in human endometrial epithelium: stage-specific expression in the menstrual cycle.

A monoclonal antibody (CC25) was obtained after immunization of mice with intact glandular epithelial cells from secretory phase endometrium. Here we report a preliminary immunohistologic study in the endometrium of 29 patients in different phases of the menstrual cycle and early pregnancy. In immunofluorescence, CC25 binds to a basolaterally oriented epithelial cell surface antigen that is absent during the proliferative phase and appears suddenly in both glandular and uterine surface locations soon after ovulation. In mid and late secretory phase, the level of expression diminishes slowly. The epitope is absent from glandular epithelial cells in first-trimester decidua. However, it is associated with vascular smooth muscle cells in endometrium and decidua. CC25 promises to be a useful reagent for the analysis of endometrial function during the menstrual cycle.