Suppression of IgE antibody production by Ascaris suum extract: characterization of suppressive component(s).

Partial characterization of the suppressive component(s) of A. suum extract that is (are) responsible for damping production of IgE antibody to ovalbumin was performed by physical and chemical methods. Digestion of the whole extract with trypsin and chymotrypsin completely abolished the suppressive activity. Oxidation with sodium metaperiodate or heating at 56 degrees C, however, had no effect. These results indicate that the integrity of heat-stable protein(s) present in the crude extract is essential for its suppressive effect. In addition, the carbohydrate moiety does not seem to play an important role in this effect.