Immunohistochemical study of the distribution of secretory component and IgA in the normal and diseased uterine mucosa.

The distribution of secretory component (SC) and IgA in the normal and diseased uterine mucosa was studied by means of an immunoperoxidase method. Both substances could not be demonstrated in ectocervical epithelium, whereas in endocervical epithelium both were present and staining intensity appeared to be related to the degree of inflammatory activity in the underlying stroma. Local IgA-containing plasma cells most likely are the source of epithelial IgA. Well-differentiated adenocarcinomas of the endocervix were shown to display SC immunoreactivity. In endometrial glands SC was observed in the postovulatory phase of the menstrual cycle, in increasing quantities toward menstruation. Hyperplastic conditions of the endometrium showed a weak focal staining for SC. In contrast, in most well-differentiated adenocarcinomas of the endometrium, SC and IgA could be detected in most neoplastic elements, whereas poorly differentiated carcinomas were largely negative. It is concluded that: (a) in contrast to the endometrium, in the endocervix a local secretory immune system operates similar to that of the gastrointestinal tract; (b) the ability of the endometrium to synthesize SC is at least partly regulated by hormonal factors and, as such, is confined to the progestagen-dominated phase of the menstrual cycle; and (c) immunohistochemical detection of SC may be of help in the grading of adenocarcinomas of the endometrium.