Expression of Fcε-receptors by human acute myelogenous leukemia (AML) blasts:: studies of high- and low- (CD23) affinity receptor expression and the effects of IgE-mediated receptor ligation on functional AML blast characteristics

Acute myelogenous leukemia (AML) blasts derived from 20 patients were examined for expression of high- (FcepsilonRI) and low-affinity (FcepsilonRII, CD23) IgE Fcepsilon-receptors. FcepsilonRI expression was not detected for any patient. In contrast, expression of CD23 (at least 15,70 of the blasts stained positive) was detected for 6 out of the 20 patients. Acute lymphoblastic leukemia (ALL) blasts derived from 12 patients did not express CD23 (< 1% positive cells for all patients). The functional effects of FcepsilonR-receptor ligation were also examined for 20 patients, including the five patients with highest CD23 expression (30-55% positive cells) and five patients with verified low CD23 expression (less than or equal to7% positive cells). The presence of I-E during in vitro culture altered the functional characteristics (spontaneous and cytokine- dependent proliferation, colony formation, cytokine secretion, or spontaneous in vitro apoptosis) of AML blasts for a subset of both CD23-positive patients and certain patients with very low CD23 expression. This last observation suggests that FcepsilonR are either expressed at a very low level or receptors are expressed only by a minor cell subset for these patients, We conclude that functional FcepsilonR can be expressed by human AML cells. (C) 2002 Elsevier Science Ltd. All rights reserved.