IL-2 and Cellular Therapy:Lymphokine-Activated Killer Cells and Tumor-Derived Activated Cells

The heterogeneity of human tumors, particularly metastatic lesions [1] has been long recongnized and therapeutically managed using both conventional [2] and biological methodologies [3]. Heterogeneity of primary or metastatic cancer, based on cell cycle, cell differentiation, tissue or organ distribution, as well as the condition of the tumor, results in differential cell surface antigen expression [4–7]. This suggests and supports the use of the recently discovered [8–10] population of cytolytic effector cells called lymphokine activated killer (LAK) cells. Although some reactivity against normal cells has been reported [11,12], the bulk of cytolytic activity is seen against tumor cells. Alternatively, methods are available to generate tumor reactive cytotoxic T lymphocytes (CTL). These cells, because of their specificity are less likely to destroy normal host itssue (See Review) [13].