Adhesive Properties of Choriocarcinoma Cells toward Lymphocytes Activated or Not by Interleukin-2

Choriocarcinoma cells (CC) in vitro are resistant to NK lysis but sensitive to lysis by blood or decidual effectors activated by interleukin-2 (IL-2). Because lytic activity requires a step of adhesion, the adhesive properties of the choriocarcinoma cells BeWo, JEG-3, and JAR were examined functionally toward peripheral blood lymphocytes. The adhesion of lymphocytes to choriocarcinoma cells was very low and did not increase after stimulating lymphocytes with IL-2. As demonstrated by cytofluorimetry analysis, choriocarcinoma cells and cytotrophoblast cells prepared from term placenta expressed intercellular adhesion molecule-1 (ICAM-1), whereas only CC expressed CD56. Tumor necrosis factor-α or interferon-γ increased the expression of ICAM-1 on choriocarcinoma cells without modifying the adhesion of lymphocytes to choriocarcinoma cells. These results suggest that resistance of choriocarcinoma cells to lysis by cytotoxic effectors could partially be attributed to the low level of lymphocyte adhesion to these cells.