Augmentation of anti-Fas antibody-mediated apoptosis on human glioma cells by liposomes associated with the antibody.

We investigated the susceptibility of five human glioma cell lines to anti-Fas antibody. All human glioma cells tested constitutively expressed Fas antigen on their surfaces and the level of the expression varied slightly in each cell line. The cells had a low susceptibility to anti-Fas antibody-mediated apoptosis. There were four moderately resistant cell lines (U251-SP, U251-MG, SK-MG-1, T98) and one highly resistant cell line (U251 nu/nu). For this study we prepared liposomes containing anti-Fas antibody and studied the augmentation of the antibody-mediated apoptosis. The liposomes induced apoptosis significantly more often than did anti-Fas antibody alone. These results indicate that anti-Fas antibody-mediated apoptosis does not require a critical level of cell surface expression of Fas antigen but rather depends on the intensity of Fas signal transduction.