Effect of purified components of Ascaris suum extracts on IgE antibody response in guinea pigs

The effect of components P530 and P29, isolated from Ascaris suum adult worm extract (ASC), on the heterologous IgE antibody response was studied in guinea pigs. Groups of 7 guinea pigs were immunized ip with 50 micrograms of ovalbumin (OA) alone or mixed with 200 micrograms of each component precipitated in an alum gel. The primary and secondary IgE antibody response was evaluated by passive cutaneous anaphylaxis reaction (PCA). Immunization of guinea pigs with P29 plus ovalbumin (OA) resulted in a significant increase in the level of serum IgE anti-OA antibodies, especially in the secondary response (almost 8-fold higher when compared with control group). This potentiated response was not observed when the animals received OA plus P530 or the crude extract. Indeed, the P530 component, as well as the crude extract, induced a depression of the anti-OA IgE antibody response (2-3 fold decrease when compared with OA-immunized animals). It was also shown that P29, but not P530 or ASC, was capable of eliciting a strong anti-ASC IgE antibody response. These results demonstrate that in guinea pigs these two Ascaris suum components have antagonistic biological effects, one inducing potentiation and the other suppression of the heterologous IgE antibody response

Suppression of the IgE antibody response by Ascaris suum components: effect of x-irradiation

The effect of X-irradiation on the supperession of IgE antibody responses induced by some of the Ascaris suum (ASC) components was analyzed in mice (7-week old A?Sn females). Treatment with 300 R 24h before immunization with 50 *g OVA and 200 *g ASC suppressive components abolished the damping effect on ati-OVA IgE antibody levels. The same effect was observed on the anti-ASC IgE antibody response obtained in mice injected with 200 *g ASC immunogenic plus 200 *g ASC suppressive components. Moreover, the failure of suppressive components to induce an IGE anti-ASC antibody response on their own was also abolished by X-irradiation. These results indicate that the suppressive components are able to elicit an IgE antibody response, but simultaneously activate a regulatory mechanism which suppressive both the homologous (anti-ASC) and heterologous (anti-OVA) antibody formation

Further characterization of ascaris suum component(s) with supressive activity on the IgE antibody response

In order to characterize the component(s) of Ascaris suum reponsible for damping of the IgE antibody production we demonstrated that the extract incubated in sodium acetate buffer, pH 4.5, maintained its suppressive effect and the same protein banding pattern by SDS-PAGE. Elimination of the lipoprotein components of the extract also left its damping properties unchanged. SDS-PAGE of the lipoprotein-free extract revealed practically the same pattern as shown by the whole extract, except for the high molecular weight polupeptides. These results indicate that the suppressive component(s) of A. suum did not precipitate and retained their activity at low pH. In addition, they appear not to be lipoproteins

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

Partial characterization ot 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-C, however, had no effect. These results indicate that the integrity of heat-stable proteins(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