Expression of leukocyte adhesion molecules in human endometrium

In the present investigation the distribution of molecules that are involved in the leukocyte binding was studied in human endometrium. The expression of intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen (LFA-1), and HLA-DR molecules was studied in 13 proliferative and 10 secretory endometria as well as cultures of endometrial glands and stroma by avidin-biotin complex (ABC) procedure using monoclonal antibodies. The ICAM-1 and HLA-DR molecules were both strongly expressed in the lymphoid and endothelial cells. ICAM-1 expression was uniform in the epithelium, whereas the HLA-DR molecules were preferentially expressed in the epithelial cells in the basalis. Expression of both epithelial HLA-DR and ICAM-1 molecules was enhanced adjacent to lymphoid aggregates. ICAM-1 molecule was uniformly expressed in the stromal cells in the basalis and the functionalis, whereas the HLA-DR molecules were expressed exclusively in the stromal cells surrounding the lymphoid cells. ICAM-1 expression in the epithelial and stromal cells was confirmed in the isolated intact stromal cells and glands by immunohistochemistry. Although stromal and epithelial cells propagated in vitro expressed ICAM-1, they were rarely HLA-DR positive. The expression of LFA-1 was confined to the lymphoid cells. The high level of expression of ICAM-1, LFA-1, and HLA-DR molecules in human endometrial constituents may contribute to the presence, aggregation, and preferential distribution of lymphoid cells in human endometrium.