Dynamic changes in viscoelastic properties in cytotoxic T-lymphocyte-mediated killing.

The biophysical properties of cytotoxic T lymphocytes during the killing of their target cells was investigated by using a human cytotoxic T lymphocyte clone, F1, and the target cell, JY, for which it is specific. In single cytotoxic cell/target cell pairs after their conjugation there are changes in the viscoelastic properties of the target cell in association with the lethal hit delivery and post-binding cytolytic steps. On the basis of these changes in the target cell, the complex cytolytic event can be divided into stages: the viscoelastic coefficients exhibited an initial increase followed by a return to resting values; thereafter these coefficients decreased below control and then rose again prior to lysis. The eventual killing of the target cell involves bubbling and swelling of the nucleus, clustering of granules, damage to the cytoplasmic membrane, cell swelling, and lysis. The viscoelastic changes involved in target cell death suggest the loss of integrity of its cytoskeletal apparatus.