Relationship Between Natural Killer Cells' Ability to Kill Leukemia Cells and the Outcome of Patients With Acute Myeloid Leukemia Previously Treated With Interleukin-2

OBJECTIVES:

• Correlate the in vitro lysis of autologous pre-treatment leukemic blast cells by interleukin-2 (IL-2)-expanded natural killer (NK) cells with relapse-free survival of patients with acute myeloid leukemia (AML) who were treated with interleukin-2 (IL-2).
• Correlate the expression of inhibitory (MHC class I) and activating ligands on AML blast cells with relapse-free survival of these patients.
• Correlate the expression of activating and inhibitory NK receptors on IL-2-expanded cells with relapse-free survival of these patients.
• Compare the susceptibility to autologous NK cell lysis of leukemic blasts obtained at diagnosis with those blasts obtained at relapse of these patients.

OUTLINE: This is a multicenter study. Patients are stratified according to age (< 60 vs ≥ 60 years) and cytogenetic risk category (favorable vs average vs poor).

Previously banked tissue samples of leukemic blast cells from bone marrow and natural killer (NK) cells from peripheral blood mononuclear cells are thawed and analyzed. Surface expression on leukemic blasts of co-stimulatory molecules, known activating NKG2D ligands, and MHC class I inhibitory ligands to NK cell receptors are quantified by monoclonal antibody analysis and flow cytometry. Mean cell fluorescence intensity (MCFI) of each ligand is correlated with relapse-free survival of the patients.