Kinetics of IgG anti IgG reaction, as evaluated by conventional and stopped flow nephelometry

Abstract

A stopped flow spectrophotofluorometer equipped with a data acquisition system was used to study the rate of formation of IgG anti IgG complexes by nephelometry. Light scattering aggregates could be detected within 100 msec. Early rates (0-3 sec) increased with antigen concentration, while rates during later stages (5-100 sec) followed the same trend exhibited by the precipitin curve. Polyethylene glycol (known to exert a profound effect on antigen antibody reactions) at a concentration of 40 g/l affected the IgG anti IgG reaction as follows: there was an initial lag phase of 5-10 sec and a subsequent rapid reaction over the next 20-40 sec, characterized by a 4-5 fold enhancement in the amount of light scattered. The observations demonstrate that centrifugal analyzer techniques can be used for the kinetic measurement of specific proteins in serum.