Modifications of leukemic blast cells induced by in vivo high-dose recombinant interleukin-2

High-dose recombinant human Interleukin-2 was given to 21 patients with acute myeloid (n = 11) or lymphoid (n = 10) leukemia in relapse. A rapid decrease in the peripheral leukemic blasts numbers was observed in six patients. We were unable to demonstrate at the bone marrow level a diminution in the percentage of leukemic blasts. However an increase in the expression of the adhesion molecule CD54/ICAM-1(LFA-1 ligand) affected the leukemic bone marrow blasts of these six patients. This increase in CD54 was found in eight of the 11 (73%) AML and four out of the ten (40%) ALL blasts and CD58/LFA-3 (CD2 ligand) to a lesser extent. This increased expression was not associated with modifications in the expression of MHC class II molecules. In vivo IL-2 also dramatically modified the bone marrow T-cell subsets via the increase of CD3+ cells expressing the CD45RO 'memory' marker (six out of the eight tested patients) or CD54 (seven out of the eight tested patients). Altogether these results demonstrate that leukemic blasts can be affected by in vivo IL-2 via mechanisms that could involve T cells.