Effect of stimulation by interferon γ and tumor necrosis factor α on CD54 expression and homotypic aggregation of blasts of acute lymphoblastic leukemias

CD54 (intercellular adhesion molecule-1, ICAM-1) surface expression on the blasts in ten cases of acute lymphoblastic leukemia (ALL) and its up-regulation by human recombinant interferon-gamma (IFN gamma) and/or tumor necrosis factor-alpha (TNF alpha) were studied in a serum-free culture system. In addition, the function of CD54 was assessed by a cellular aggregation assay. Prior to in vitro culture, only 3/10 ALL cases had more than 20% CD54-positive blasts. A 24-h incubation in serum-free medium alone induced CD54 positivity in another two cases. In these two ALLs, stimulation with IFN gamma and/or TNF alpha further enhanced CD54 positivity. In addition, TNF alpha induced CD54 expression in one fur ther case. In the remaining four cases no CD54 expression was induced by either cytokine. Of the six cases with constitutive or inducible CD54 expression, only five displayed CD54-dependent cellular aggregation. Taken together, the ALLs studied were heterogeneous with respect to their constitutive and cytokine-driven CD54 expression, while TNF alpha seemed to be more effective than IFN gamma. In most cases, the CD54 molecule was functionally active, in that CD54 expression was paralleled by CD54-dependent homotypic aggregation of the blasts.