SOLUBLE FC-GAMMA-RIII IS PRESENT IN LOWER CONCENTRATIONS IN THE SERUMOF PATIENTS WITH ACUTE MYELOGENOUS LEUKEMIA (AML) - A RETROSPECTIVE STUDY

FcgammaRIII is a low affinity immunoglobulin G receptor expressed by n eutrophils, natural killer cells, and macrophages. Soluble forms of Fc gammaRIII have been identified in serum, plasma, and other body fluids . Previous studies showed that FcgammaRIII appeared late in myeloid di fferentiation. This retrospective study was designed to measure the co ncentration of soluble FcgammaRIII in serum from patients with acute m yelogenous leukemia (AML), a disease generally characterized by granul ocytopenia and an increase in circulating myeloblasts and occasionally promyelocytes. Frozen serum samples from patients with AML and from a ge-matched normal donors were obtained from the Biological Carcinogene sis Branch Repository of the National Cancer Institute. We used an ELI SA to measure the concentration of soluble FcgammaRIII in these serum samples and observed significantly lower concentrations of soluble Fcg ammaRIII in the serum of AML patients. The mean concentration of solub le FcgammaRIII was 9.5 nm in normals (n = 48) and 5.4 nm in AML patien ts (n = 46), (p < 0.0005). Whether this difference is due to defects i n granulopoiesis in these patients or to other parameters of the disea se is unknown al this time. Our retrospective study should provide the basis for subsequent investigation of patients with AML to correlate soluble FcgammaRIII concentrations with the clinical status of the pat ients.