A Novel Method for the Assay of Complement Activity Using Immunoliposomes and Its Clinical Application

Abstract

We developed a method for measuring the total and alternative pathway activities of the complement system using rabbit γ-globulin (RGG)-coupled liposomes and anti-RGG antibody. The lysis of these liposomes in the present system as well as the hemolysis in the conventional method was expressed by von Krogh's equation. The reproducibility of the present method was satisfactory. The total activity and the activity of the alternative pathway measured by the present method were correlated to the activity measured by the conventional Mayer's method (r=0.555 and 0.351, respectively). Measurement of the complement activities in healthy subjects revealed that the total activities measured by the present method and the activities measured by Mayer's method increased with age, but the activities of the alternative pathway were independent of age. Furthermore, the total activities measured by the present method in diabetic subjects were lower than those in healthy subjects. However, there was no significant difference in the activities measured by Mayer's method between diabetic and healthy subjects. These findings, as well as the homogeneity of the liposomes and the simplicity of these preparation, suggested that the present method using liposomes could be a new clinical parameter for measurement of the complement activities.