Estimation of the True Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) Autoantibody Concentration in the Sera of Normal Subjects

Abstract

According to our previous studies, Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) autoantibodies (GMAbs) are normally present in healthy people. To date, antigen-antibody capture assay has measured the concentrations. However, nonspecific IgG other than GMAbs and immune complex formation with intrinsic GM-CSF prevents us from measuring the accurate concentrations. To solve these problems, we developed a liquid phase high-sensitivity assay using biotinylated GM-CSF (bGM-CSF) and streptavidin coated plate, which could measure the concentration of GMAbs over 0.02 ng/ml. Using this method, the true GMAbs concentration in 30 normal subjects was estimated to be 52.6 ng/ml for the median value, ranging 10.6 to 799.5 ng/ml. Thus, we propose a novel method that enables us to estimate the true concentration of GMAbs in the sera of healthy subjects.