Immunohistochemical demonstration of alpha-1-antitrypsin and alpha-1-antichymotrypsin in normal human endometrium.

Forty-five specimens of endometrium, consisting of 10 proliferative, 10 each of early, mid-, and late secretory, and five menstrual phase, were examined with antibodies to alpha-1-antitrypsin (A1AT), alpha-1-antichymotrypsin (A1ACT), muramidase, and serum 22, using an indirect peroxidase-antiperoxidase immunoperoxidase technique. Five postmenopausal and 10 pregnancy endometria were also examined. Very few macrophages were detected. Other stromal cells, however, in premenopausal, nonpregnant endometrium, stained strongly for A1AT and A1ACT but not with the other two antisera. Stromal cells following the menopause did not stain nor did the decidual cells of pregnancy. Only rare, isolated epithelial cells or whole glands stained for A1AT and A1ACT. The function of these antiproteases in endometrium may be to regulate the protease activity of the implanting blastocyst or the immunological response to it.