Detection of intermediate complexes by evaluation of the difference between gamma-globulin and IgG concentrations

A simple analysis based on techniques readily available in the routine clinical laboratory has been presented for identification of patients with moderate and high levels of intermediate complexes. If the gamma-globulin concentration determined by serum protein electrophoresis minus the IgG concentration determined by radial immunodiffusion exceeds 1.0 gm/dl, intermediate complexes of IgG should be present in concentrations greater than 0.5 gm/dl. In principle, any disease association with sufficient polymerization of IgG might cause an abnormal result with this analysis. Furthermore, sera from patients with liver disease and marked beta-gamma-bridging on electrophoresis may also give abnormal values.