Lytic granules, adhesion molecules, and other recent insights

Probably the most exciting of the insights into the mechanism of cell-mediated lysis reported at a recent workshop was the cytolytic activity detected in granule preparations from large granular lymphocytes with natural killer activity, tumor cells and cloned lines of cytotoxic lymphocytes (TC). For the first time, several labs agree on the existence of cell-free mediators with properties which make them attractive candidates for the lytic effector molecules employed by TC as well as NK cells. Such results were reported by Pierre Henkart (NIH, Bethesda), Eckhard Podack (New York Medical College, Valhalla), and john Ding-E Young (Rockefeller Univ., New York). At sufficient concentrations, these granule preparations can effect complete lysis of P815 or EL4 tumor cell populations within minutes.