[Immune complexes in the serum of patients with acute myeloblastic leukemia].
This study was performed to determine whether the nature of the hemolytic factor present in 54% of sera collected from patients during the active stage of acute myeloid leukemia (AML) [1] is immune complex (IC)-like. The fluid phase C1q-binding test (C1q-BT) served to analyze 92 sera from 24 patients with AML. In a first study the C1q-BT as modified by Carpentier [2] was compared to the universally accepted C1q-BT as described by Zubler [3]. Binding of C1q to heat aggregated human IgG, to tetanus toxoid (Te)/anti-Te complexes, and to serum containing heparin or fibrinogen was to a similar extent concentration-dependent; however, the binding values obtained with the method of Carpentier were always higher than with the method of Zubler. The same was found for the binding of C1q to sera from patients suffering from various diseases: using Carpentier's method approximately a 20% higher C1q-binding activity was found for all samples compared to binding activities found with Zubler's original method. The higher C1q binding did not depend on higher sensitivity of Carpentier's assay system, as the binding to sera from 60 healthy individuals was also elevated (8.1 +/- 6.0% vs 1.2 +/- 1.0% with the method of ZUBLER). In a second study AML sera were analyzed by the "extended" C1q-BT [4]. The "extended" C1q-BT uses two different C1q preparations and the assay follows the procedure described by ZUBLER. This test is able to detect immune-aggregate-mediated and non-immune-aggregate-mediated C1q binding.(ABSTRACT TRUNCATED AT 250 WORDS)