The most efficient cytotoxic T lymphocytes are the least susceptible to lysis
Skinner, M.; Marbrook, J.
Journal of Immunology 139(4): 985-987
1987
ISSN/ISBN: 0022-1767 PMID: 3497201 Document Number: 290162
When a cytotoxic T cell (CTL) kills the appropriate target cell, antigen recognition by the T cell receptor is followed by delivery of the lethal hit. The target cell lysis is a polarized event, and the CTL appears to be unaffected by the killing process. It was shown in early experiments that reactive CTL are themselves susceptible to appropriate lysis, because "A anti-B" CTL could decrease the activity of "B anti-C" CTL (1, 2), and similar results were obtained by using lectin-dependent T cell-mediated cytotoxicity (3). With the ability to maintain and grow CTL clones and hybridomas in vitro, it has been possible to use cloned CTL as both effector and target cells and although CTL clones cannot kill themselves, they are able to kill other CTL clones and hybridomas of different specificities in the presence of PHA (4). In these studies, the inability of CTL clones to kill themselves has been investigated by using an anti-hapten system. By chemically modifying cytotoxic cells, they acquire the potential for self-recognition and lysis. We have taken a series of anti-fluorescein-specific CTL that recognize antigen in the context of H-2d and have demonstrated that there is no self killing of fluoresceinated cells with any of the clones. In addition, there is a hierarchy in the efficiency with which clones kill which correlates with their resistance to lysis. As a basis for future investigations, a possible intracellular mechanism is postulated that explains why the most potent killers appear to be the most resistant target cells and killing of modified self killers is not observed.