HUMAN ENDOMETRIAL STROMAL CELLS AS A SOURCE OF SOLUBLE INTERCELLULAR-ADHESION MOLECULE (ICAM)-1 MOLECULES

Intercellular adhesion molecule (ICAM)-1-mediated cell-cell adhesion i s essential for various immunological functions, including natural kil ler (NK) cell-mediated cytotoxicity against endometrium, The present s tudy was designed to establish whether shedding of ICAM-1 from culture d endometrial stromal cells occurred and to characterize its potential functional significance in endometrial physiology and pathology, The shed sICAM-1 molecule was detected and quantified in supernatants from endometrial stromal cultures and in peritoneal fluids by a specific e nzyme-linked immunosorbent assay, The results of this study indicate t hat cultured endometrial stromal cells constitutively shed ICAM-1 from their surface, This ability is regulated during the menstrual cycle, as it appears to be higher in the proliferative than ire the secretory phase of the cycle (16.93 +/- 2.2 and 7.7 +/- 1.76 ng/ml respectively ). In order to evaluate whether the release of sICAM-1 could interfere with cell-mediated lysis of endometrium, we compared the determinatio ns of sICAM-1 in endometrial supernatants with the ability of such sup ernatants to suppress NK cell-mediated cytotoxicity toward endometrial targets, A significant correlation (r = 0.6, P < 0.05) was found betw een the sICAM-1 concentration in endometrial supernatants and the perc entage of inhibition of NK cell-mediated lysis exerted by the same sup ernatant samples, Finally, endometrial stromal shedding of sICAM-1 app ears to be related to endometriosis since endometrial stromal cultures obtained from patients with advanced stages of the disease released s ignificantly higher amounts of the soluble protein compared to the con trol group (P < 0.05), sICAM-1 is a soluble molecule which can interfe re with immunological functions, and its shedding may be one of the me chanisms by which refluxed endometrial cells escape immunosurveillance .