Extracts of Ascaris suum egg and adult worm share similar immunosuppressive properties

Adult Ascaris suum body extract (Asc) prepared from male and female worms (with stored eggs) down-regulates the specific immune response of DBA/2 mice to ovalbumin (OA) and preferentially stimulates a Th2 response to its own components, which is responsible for the suppression of the OA-specific Th1 response. Here, we investigated the participation of soluble extracts prepared from male or female worms or from eggs (E-Asc) in these immunological events. Extracts from either sex (1 mg/animal) or E-Asc (0.35 or 1 mg protein/animal) suppressed the delayed-type hypersensitivity (DTH) reaction (60-85 percent), proliferative response (50-70 percent), IL-2 and IFN-gamma secretion (below detection threshold) and IgG1 antibody production (70-90 percent) of DBA/2 mice to OA. A dose of 0.1 mg E-Asc/animal did not change DTH or proliferation, but was as effective as 0.35 mg in suppressing IL-2 and IFN-gamma, and OA-specific IgG1 antibodies. Lymph node cells from DBA/2 mice injected with Asc (1 mg/animal) or a high dose of E-Asc (1 mg protein/animal) secreted IL-4 upon in vitro stimulation with concanavalin A. As previously demonstrated for Asc, the cytokine profile obtained with the E-Asc was dose dependent and changed towards Th1 when a low dose (0.1 mg protein/animal) was used. Taken together, these results suggest that adult worms of either sex and eggs induce the same type of T cell response and share similar immunosuppressive properties

Colorimetric assay for the measurement of thymocyte/thymic stromal cell adhesion

1. We describe a simple and accurate colorimetric adhesion assay (CAA) and illustrate the assay by measuring the adhesion of mouse thymocytes to mouse 2BH4 cells. 2. The assay is based on the crystal violet staining of thymocytes adhered to a subconfluent layer of 2BH4 cells (plated at 2 x 10(4) cells/well for 24 h). The optimal incubation time was shown to be 1 h and washing in PBS of non-bound and non-specifically bound thymocytes is the critical step for the precision and accuracy of the assay. 3. Saturation curves were obtained for thymocytes adhered to plated 2BH4 cells. The blank (only 2BH4 cells) was near 0.200 +/- 0.010 (mean +/- SD) and was quite reproducible. As expected, the extent of adhesion was also dependent on the number of plated 2BH4 cells. Standard curves need to be run with each assay for quantitative measurements. The intra-assay and interassay coefficients of variation were 5 and 20, respectively. 4. The specificity of the reaction was demonstrated by the reduction of adherence by trypsin pretreatment of thymocytes, and the dose-dependent inhibition of adherence by rabbit anti-mouse thymocyte antisera but not rabbit anti-mouse immunoglobulin antisera. 5. The proposed method is simple and requires less effort than the counting of adhered cells with the light microscope and does not require the use of radioactive material as when labelling with Na2(51)CrO4 is utilized.

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

Paf antagonists do not modify IgE antibody production in mice

The effect of selective PAF antagonists on the in vivo production of IgE antibodies was investigated. The anti-ovalbumin IgE antibody content was estimated by passive cutaneous anaphylactic reaction (PCA) in the plasma of Balb/c mice 10 days after immunization with ovalbumin and alum. The PAF antagonists, BN 52021 (5 mg/kg, ip), BN 50730(20 mg/kg, ip) BN 50730 (20 mg/kg, po), WEB 2086 (2 mg/kg, ip) and WEB 2170 (5 mg/kg, ip) were administered 1 h before immunization and twice a day for 8 days thereafter. The effect of the antagonists on the PAF-induced vasopermeability was also assayed. In the immunized mice the level of antiovalbumin IgE antibody, estimated by PCA titer, was 1/640. The treatment with the PAF antagonists did not change this level. At the concentrations employed, the antagonists BN 50730, WEB 2086 and WEB 2170 significantly reduced the PAF-induced vascular permeability. These results suggest that PAF does not seem to have a relevant effect on the production of IgE antibodies in vivo in the system used in the present study

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

Murine delayed type hypersensitivity is suppressed by Ascaris suum extract

We studied the suppressive effect of an Ascaris suum extract on delayed-type hypersensitivity (DTH) reactions to ovalbumin (OVA) and to Bacillus Calmette-Guerin (BCG). The ability of mice to develop DTH reactions to both antigens was suppressed when an immunizing dose of the antigen was given subcutaneously together with the Ascaris extract. Partial or complete suppression of the response to OVA was obtained by the use of 400 por 1000 microng of Ascaris extract, respectively. The response to BCG, on the other hand, was totally suppressed by 400 microng of extract

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