NK binding capacity and lytic activity depend on the expression of ICAM-1 on target bone tumours

Osteosarcoma cell lines are differently lysed by natural killer (NK) lymphocytes. A critical step in the lytic process is the recognition and attachment of effector to target cells. To determine binding capacity and lytic activity of NK cells, we investigated the distribution and role of ICAM-1, 2 and 3 on two osteosarcoma cell lines (HOS and Saos-2) in basal conditions and after TNF alpha treatment. Modulation of ICAM-1 after TNF alpha treatment modified the binding capacity of NK cells to osteosarcoma target cells. This modulation process appears to play a critical role in determining the susceptibility of these cells to NK-mediated lysis