Recent approaches to induction of cytotoxic lymphocytes against leukemia.

We have shown that therapy of AML patients in second remission with continuous infusion of IL-2 resulted in generation of cytotoxic lymphocytes in peripheral blood and bone marrow. However, these lymphocytes mediated cytotoxicity only against tumor cell lines, and not against AML blasts. Additional in vitro activation with higher dose of IL-2 was necessary for induction of AML blast oncolysis. This indicates that the concomitant treatment with continuous and periodic bolus IL-2 infusion may be necessary, to achieve higher levels of IL-2 and subsequently, more potent lymphocyte activation. Alternatively, it may not be possible to induce optimal antileukemia response in vivo with tolerable doses of IL-2, and the adoptive therapy with in vitro supremely activated lymphocytes may represent an option. In this article, we discuss several approaches to the supreme activation of cytotoxic lymphocytes against highly resistant AML blasts and their possibilities in leukemia therapy.