[Morphological observation of human LAK cell killing activity on lung adenocarcinoma cells]

LAK activity could be induced by IL-2 from human PBL. After co-culture of LAK cells with Anip973 human lung adenocarcinoma cells, LAK-tumor conjugates were microscopically observed. Formation of the conjugates paralleled well with the expression of LAK activity (P less than 0.001), suggesting that LAK cells' killing of Anip973 cells depended on their close contact. Under electron microscope, LAK cells had various shapes and certain degrees of motility. Ten minutes after co-culture, close binding between microvilli of LAK cells and tumor cells could be seen. Four hours after co-culture, Anip973 cells bound with LAK cells developed numerous membrane blebs with cytoplasm and nucleus very condensed, which was followed by destruction of cell structure and appearance of cell debris. These features are consistent with apoptosis rather than a cytolytic mechanism of cell death. These findings suggest that LAK cells share certain common features with CTL and NK cells on killing tumor cells.