IgG2 antibodies block IgE antibody-induced asthma in guinea pigs

In order to examine the blocking activity of IgG2 antibodies to guinea pig for IgE antibodies-induced guinea pig asthma, experiments were carried out as follows. Guinea pigs were passively sensitized intravenously with guinea pig serum containing IgE antibodies to ovalbumin (OA). 8 days after sensitization, IgG2 purified from guinea pigs hyperimmunized with OA was intravenously injected. One hour later, the guinea pigs were challenged by inhalation of OA solution. Asthma attacks were not observed in the guinea pigs, whereas the attacks were observed in guinea pigs passively sensitized with the IgE antibodies but injected IgG2 fraction from normal guinea pigs 1 h before inhalation. These observations suggested that IgG antibodies that increased after immunotherapy might block asthma caused by inhalation of allergens in humans.