Intercellular adhesion molecule-1 is expressed on human granulosa cells and mediates their binding to lymphoid cells.

Some immune cellular components have been recently demonstrated to play a critical role in ovarian physiology. Resident ovarian white blood cells are known to produce cytokines that modulate granulosa cell (GC) functions and differentiation. Moreover, it has been postulated that, during the formation of the corpus luteum and luteolysis, human luteal cells are able to interact with lymphocytes and macrophages through some adhesion molecules. This study was designed to examine, at messenger RNA and protein levels, whether intercellular adhesion molecule (ICAM)-1, known to be involved in leukocyte-cell binding, is expressed by human GCs. Furthermore, we also investigated whether this molecule could be involved in the complex events that allow the interaction between the ovary and the immune system. GCs, obtained from women undergoing in vitro fertilization procedures, were enzymatically dispersed with collagenase and cultured for different time periods. To assess the presence of ICAM-1 messenger RNA, total RNA obtained from freshly aspirated GCs and GCs luteinized in culture was reverse transcribed and then amplified using two oligonucleotide primers specific for the human ICAM-1 gene. A single major DNA band of the expected size (943 bp) was obtained. The identity of this material with the human ICAM-1 sequence was further confirmed by restriction enzyme analysis. Surface ICAM-1 protein was detected by flow cytometric analysis on luteinized GCs cultured for 7 and 15 days. Finally, to evaluate a possible functional activity of ICAM-1, a 51Cr-release-binding assay between peripheral blood lymphocytes and luteinized GCs was performed in the presence and absence of a monoclonal antibody against ICAM-1. As a result, lymphocyte adhesion to GC monolayers was significantly, but not completely, inhibited by the anti-ICAM-1 monoclonal antibody. These findings demonstrate that intercellular interactions between GCs and the immune system are, at least in part, mediated by the adhesion molecule ICAM-1. Based on this data, we might speculate that this molecule could participate in the remodeling processes of the ovarian endocrine compartment.