[Non-specific killer cells in tumor immune response].

This article focuses on the roles of natural killer (NK) cells and lymphokine-activated killer (LAK) cells in immune surveillance against malignant tumors. NK cells have a natural and also rapidly activatable ability to lyse a variety of tumor cell lines. There is considerable evidence for the ability of NK cells to eliminate metastatic tumor cells and thereby resist tumor spread. There is also a correlation between increased tumor incidence (primarily lymphoma) and depressed NK activity. Therefore, NK cells appear to contribute to antitumor resistance, especially against the microevolution of tumor cells and metastasis. LAK cells, which can be induced by a lymphokine, interleukin 2, in a subset of NK cells, express cytotoxic activity toward an extensive spectrum of histologically distinct fresh autologous tumor cells. Fresh tumor cells resistant to lysis by NK cells are extremely sensitive to lysis by LAK cells. Although the biological role of these cells is presently unknown, their characteristics also point toward an important function in immune surveillance.