Pulse immunoassay for human immunoglobulin G using antibody bound latex beads

Pulse immunoassay was applied in the immunoassay of human immunoglobulin G (H-IgG). Antibodies to H-IgG were covalently immobilized on the surface of latex beads (1 microM). Immunoreaction of the antibody bound latex beads (Ab-L) and H-IgG was performed using electric pulses. Agglutination rate (AR), defined by the following equation, was used to estimate the immunoreaction rate (formula; see text) where Nn is the total number of beads forming n bead agglutinations. Each Nn was determined by analyzing photographs of the samples. When 140 microliter of Ab-L suspension (0.7%) containing H-IgG (6.7 X 10(-6) g ml-1) was reacted using electric pulses (peak height 2 kV cm-1, pulse width 20 microseconds, pulse frequency 8 kHz), AR increased sharply and reached 50% after 10 min. In contrast, when the same sample was reacted without electric pulses, AR increased very slowly and only reached 20% after 20 min. Therefore, the immunoreaction of H-IgG and Ab-L can be carried out more rapidly by applying electric pulses.