Interferon gamma induces intercellular adhesion molecule-1 on murine midterm trophoblast and enhances susceptibility to specific lysis by paternally directed allo-immune cytotoxic T cells.

Expression and function of intercellular adhesion molecule-1 (ICAM-1) on murine trophoblast cells and its regulation by interferon gamma (IFN-gamma) were investigated. Flow cytometry was used to detect ICAM-1 and class I major histocompatibility complex (MHC) antigen expression, while a 51Cr release assay was used to investigate the role of ICAM-1 in cytotoxic T lymphocyte (CTL)-mediated lysis and the effect of anti-ICAM-1 antibody blockade on lysis. We found that murine trophoblasts cells from midterm pregnancy (Day 14 postcoitum) express low or undetectable ICAM-1 and MHC antigens but that these are readily inducible by IFN-gamma. Untreated cells resisted lysis by allospecific CTL however, after treatment with IFN-gamma for 72 h, these trophoblasts were readily susceptible to lysis by allospecific CTL. The lysis was significantly reduced by anti-ICAM-1 antibody blocking. This finding which indicates that ICAM-1 can take part in CTL-mediated lysis of midterm trophoblast, has potentially important implications in vivo for the immunological relationship between mother and fetus.