CELL-SURFACE EXPRESSION OF ICAM-1 (CD54) AND LFA-3 (CD58), 2 ADHESION MOLECULES, IS UP-REGULATED ON BONE-MARROW LEUKEMIC BLASTS AFTER INVIVO ADMINISTRATION OF HIGH-DOSE RECOMBINANT INTERLEUKIN-2

High-dose recombinant interleukin-2 (rIL-2) therapy can induce long-term remission in patients with melanoma and renal and colon cancer. More recently, in vivo IL-2 therapy was shown to induce complete or partial remission in some cases of relapsed chemotherapy-resistant acute myeloid leukemia. We have investigated the phenotypic modifications of bone marrow cells obtained from five patients with acute myeloid leukemia in relapse receiving high-dose i.v. rIL-2. We found that, in three of five patients, IL-2 could induce, in vivo, an increase in the expression of CD54/ICAM-1 and to a lesser extent of CD58/LFA-3 on bone marrow leukemic blasts. This demonstrates that rIL-2 modifies directly or indirectly the expression of the cell surface molecules of the tumor cells themselves. Upregulation of such adhesion molecules could account for the enhancement of cell interactions between the tumor and effector cells such as T, natural killer, and phagocytic cells as well as being indicators of differentiation signaling. eloid leukemia.