Presence of Schistosoma mansoni antigens in liver, spleen and kidney of infected mice: a sequential study

In the present study the kinetics of the uptake and deposition of Schistosoma mansoni antigens in liver, spleen and kidney of S. mansoni infected Swiss mice have been investigated in relation to duration of infection and infection dose (50, 100, 200 cercariae). The presence of antigen was studied with a direct immunofluorescence reaction on frozen sections of the organs, using a number of fluorescein isothiocyanate (FITC)-labeled antisera produced against various antigen preparations isolated from different life-cycle stages of the parasite. The presence of antigen was demonstrable with two of the antisera, directed against the circulating anodic antigen (CAA) and against total soluble egg antigen (SEA). CAA was demonstrable from 1 week post infection (p.i.) onwards in Kupffer cells in the liver, from 2-3 weeks p.i. onwards in macrophages in the marginal zones in the spleen and from 3 weeks onwards in kidney glomeruli. Immunofluorescence reactions on CAA in kidney glomeruli, however, were only weak positive until 12 weeks p.i., whereafter strong positive reactions were found. SEA was demonstrable from 5 weeks p.i. onwards in Kupffer cells in the liver and from 4 weeks p.i. onwards in macrophages of the spleen. In contrast to CAA, SEA was not detectable in kidney glomeruli.

Schistosoma japonicum: immunological response to circulating polysaccharide antigens in rabbits with a light infection

To study the detectability of circulating polysaccharide antigens and the immunological response to such antigens in rabbits with a light Schistosoma japonicum infection, sera of five rabbits infected with 50 cercariae were studied up to 29 weeks post infection (p.i.). While one rabbit developed no worm burden, the other rabbits developed low worm burdens (4 to 16 worms). In the sera of these rabbits, the only polysaccharide antigen demonstrable with immunoelectrophoresis (IEF), was the circulating anodic antigen (CAA). With the enzyme-linked immunosorbent assay (ELISA), CAA was detectable from 5 to 6 weeks p.i. in the sera of the two rabbits with the highest number of worm couples. The lowest CAA level which was detectable in unconcentrated sera from which serum proteins had been removed was 125 ng CAA/ml, corresponding with a worm burden of 4.5 worm/kg body wt. During the entire infection, CAA-specific immune complexes were only demonstrable in very low concentrations. Antibodies against polysaccharide antigens were assessed with immunofluorescent antibody (IFA) on Rossman's fixed sections of adult worms, with the ELISA, and with IEF. Specific IgA, IgG, and IgM antibodies were detectable from 2 to 3 weeks p.i. with IFA and ELISA. These early antibodies were shown to be directed against gut-associated antigens, while antibodies against parenchyma-associated antigens were found later in the infection. With IEF, antibodies against two trichloroacetic acid (TCA)-soluble antigens were detectable, including the major, S. japonicum-specific antigen 2.

Schistosoma japonicum: immunological characterization and detection of circulating polysaccharide antigens from adult worms

The antigenic constituents of a trichloroacetic acid (TCA)-soluble fraction of adult Schistosoma japonicum were studied with immunoelectrophoresis, and compared with those of Schistosoma mansoni. Eight TCA-soluble antigens of S. japonicum were demonstrated, five of which showed immunological identity with S. mansoni antigens. Of the eight antigens, five antigens with anodic motility were found as circulating antigens in S. japonicum-infected hamster and rabbit sera; the major circulating antigen was the circulating anodic antigen (CAA). Two other antigens, with cathodic motility, including the circulating cathodic antigen (CCA), were demonstrable as circulating antigens in S. mansoni infections, but not in S. japonicum infections. Most of the circulating antigens were shown to be gut-associated. Only one antigen, line 2, which was not demonstrable as circulating antigen and which was present in the parenchyma of the worms, was found to be specific for S. japonicum. Using an ELISA for the detection of CAA in the sera of S. japonicum-infected rabbits, a lower detection level of 100 ng CAA/ml serum was achieved. Moreover, at 7-8 weeks after infection, a direct relationship between worm burden and CAA level was demonstrated.

A monoclonal antibody from infected mice to a Schistosoma mansoni egg proteinase

A number of monoclonal antibodies were obtained by fusion of SP2/0 myeloma cells and spleen lymphocytes from mice infected with Schistosoma mansoni. These antibodies were tested for their ability to inhibit acidic, thiol-dependent proteinases previously isolated from Schistosoma mansoni eggs and adult worms. One of the monoclonal antibodies isolated inhibits egg proteinase activity measured in vitro with the use of a low m.w. synthetic substrate. This antibody, which is an IgG1 isotype, does not appreciably inhibit an acidic, thiol-dependent proteinase obtained from the adult stage of Schistosoma mansoni. Immunocytochemical methods with the monoclonal antibody have been used to localize the egg proteinase within a set of "penetration" glands in the unhatched miracidium.

A monoclonal antibody from infected mice to a Schistosoma mansoni egg proteinase

A number of monoclonal antibodies were obtained by fusion of SP2/0 myeloma cells and spleen lymphocytes from mice infected with Schistosoma mansoni. These antibodies were tested for their ability to inhibit acidic, thiol-dependent proteinases previously isolated from Schistosoma mansoni eggs and adult worms. One of the monoclonal antibodies isolated inhibits egg proteinase activity measured in vitro with the use of a low m.w. synthetic substrate. This antibody, which is an IgG1 isotype, does not appreciably inhibit an acidic, thiol-dependent proteinase obtained from the adult stage of Schistosoma mansoni. Immunocytochemical methods with the monoclonal antibody have been used to localize the egg proteinase within a set of "penetration" glands in the unhatched miracidium.

Scanning electron microscopical observations on antigen-antibody coat formation on mechanically transformed Schistosoma mansoni schistosomula

As part of a study of the antigenic composition of the tegument of mechanically transformed Schistosoma mansoni schistosomula, the phenomenon of coat formation around such schistosomula when incubated in medium containing serum of S. mansoni infected mice was investigated with light and scanning electron microscopy. Coat formation was only observed on freshly transformed schistosomula, while schistosomula that had been incubated overnight at 37 degrees C in medium without serum from infected mice were no longer able to produce a coat. When freshly transformed schistosomula were incubated in medium containing serum from infected mice, it was found that individual spines on the tegument were covered with a coat within 1 h. After 2 h of incubation, the schistosomula were completely covered with a thick coat, starting at the posterior end. This coat was actively shed by the schistosomula after 3 h of incubation. To investigate the mechanism of coat formation, experiments were carried out using serum from uninfected mice, heat-inactivated serum from infected mice, and the IgG fraction of serum from infected mice. From the experiments it was concluded that the coat consisted of antigen-antibody complexes, involving IgG antibodies and complement. A detailed analysis of the easily obtainable coats may lead to a better understanding of the antigenic structure of the cercarial and schistosomular tegumental membrane.

A comparative study on the preparation of immunoglobulin-galactosidase conjugates

For the application of beta-D-galactosidase-immunoglobulin conjugates in the enzyme-linked immunosorbent assay (ELISA), four techniques for the preparation of such conjugates were compared. Sheep immunoglobulin (Ig) (against soluble egg antigens of the trematode Schistosoma mansoni) was coupled to beta-D-galactosidase by means of 1) glutaraldehyde treatment, 2) the heterobifunctional reagent N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP), and 3,4) two different procedures using the coupling agent m-maleimidobenzoyl-N-hydroxysuccinimide ester(MBS). The prepared conjugates were then fractionated by gel filtration on Sepharose 6B and the resultant molecular weight fractions were tested in an ELISA for the detection of S. mansoni antigen. Optimal results were obtained with a conjugate that was synthesized according to one of the two techniques using MBS. With this conjugate, 10(-9) g antigen/ml could still be detected in an ELISA with a chromogenic substrate, which was at least ten times as sensitive as with the other conjugates. Application of a fluorogenic substrate resulted in a lower detection level of 10(-10) g antigen/ml.

Renal disease in chronic experimental Trypanosoma gambiense infections

Two recently isolated stocks of Trypanosoma brucei gambiense of human origin gave rise to a moderate to severe proliferative or membranoproliferative glomerulonephritis in 40 or 44 NMRI and C57BL/6J mice infected for 7-22 weeks. Extensive granular deposits of C3, IgG1 and IgG3 were found in the mesangium, together with smaller quantities of IgG2a, IgG2b, and IgM. No trypanosomal antigen could be detected in the deposits though specific anti-trypanosoma antibodies were found in kidney eluates. By electron microscopy, a conspicuous proliferation of mesangial and endothelial cells was observed and electron-dense deposits were seen in a mesangial and subepithelial localization. With one of these trypanosome stocks, four of seven Wistar rats infected for 9-15 weeks developed morphologically similar glomerular lesions. Four other trypanosome stocks did not evoke renal alterations in 17 other rats infected for 13-56 weeks. Experimental infection in mice or rats appears to be a suitable model for the study of renal disease in chronic African sleeping sickness.

Immunodiagnosis of recently acquired Schistosoma mansoni infection. A comparison of various immunological techniques

A group of Dutch tourists, who became infected with Schistosoma mansoni in Ethiopia, was investigated in a serological follow-up study, during 8-50 weeks after infection. The following immunodiagnostic tests were applied: (1) the immunofluorescent antibody (IFA) test, both on frozen sections of adult worms, and in a modification for the detection of antibodies against gut-associated polysaccharide antigens; (2) the enzyme-linked immunosorbent assay (ELISA) with as antigens: adult worm antigens (AWA), cercarial antigens (CA), soluble egg antigens (SEA), and the purified antigens CAA and MSA1; (3) the defined antigen substrate spheres system with AWA as antigen in an immunofluorescence and immunoperoxidase modification; (4) the indirect haemagglutination reaction with AWA; and (5) the immunoelectrophoresis with AWA and antigens of the intermediate host. With these techniques it could be shown that in all persons which had been in contact with S. mansoni infected water, also in those not excreting schistosome eggs or not showing clinical symptoms of infection, specific anti-schistosome antibodies were present. No false-negative reactions were found with the ELISA with cercarial antigens, MSA1, or AWA-TCA, with the IFA detecting gut-associated polysaccharide antigens and with the immunoelectrophoresis. The highest titres were observed with the two techniques (IFA and ELISA) detecting antibodies against the gut-associated polysaccharide antigen CAA.

The implantation of sepharose beads in mouse livers as an aid in the study of hepatic schistosomal fibrosis

An experimental model of schistosomal portal fibrosis is described. Sepharose beads the size of schistosome eggs, loaded or not with soluble egg antigen (SEA) from Schistosoma mansoni, are injected into the coecal vein of C3H/Sn mice and become embolized in the liver. Only SEA-coated beads evoke a granulomatous reaction; this is enhanced by simultaneous priming of the mice with spleen cells from Schistosoma mansoni-infected syngeneic animals. The fibrosis, which ensues around the beads, is stable and is much more evident after priming. Preliminary collagen tissue immunotyping reveals the presence of collagen deposits of types I and III collagen. Type IV collagen remains unchanged in the portal tracts. The model appears to be well suited for studies of the pathogenesis of portal fibrosis.

Automated measurement of immunogalactosidase reactions with a fluorogenic substrate by the aperture defined microvolume measurement method and its potential application to Schistosoma mansoni immunodiagnosis

For automated read-out of immunogalactosidase assays with a fluorogenic substrate, performed in microtitration trays, an inverted fluorescence microscope equipped with a photometer and a scanning stage and operated by a microprocessor has been used. Trays (60 and 96 wells) were scanned in 1 min and corrected measurements and a histogram of the results printed out in a few minutes. A lower level of 4 ng of the reaction product, 4-methylumbelliferone, was detected. By making the measuring system flexible we were also able to use it for fluorescence measurements of individual agarose beads or cells and for extinction measurements in ELISA reactions with a chromogenic substrate. On comparing FITC and galactosidase conjugates in a DASS-test, and peroxidase and galactosidase conjugates in an ELISA, with Schistosoma mansoni infection as test system, it appeared that the galactosidase modification of both assays was 30-50 times more sensitive than the FITC or peroxidase modification. For S. mansoni egg antigen, a lower detectable level of 0.1 ng antigen/ml was achieved.

Applicability of different antigen preparations in the enzyme-linked immunosorbent assay for schistosomiasis mansoni

The applicability of seven different antigen preparations for the detection of antibodies against Schistosoma mansoni was tested in the enzyme-linked immunosorbent assay. For this purpose, sera from children and adults from Surinam infected with S. mansoni were screened for the presence of specific antibodies against the various antigens. With all antigens, generally better results were obtained with the sera from children than with those from adults. The best results were obtained when the trichloroacetic acid-soluble fraction of adult worm antigen (containing the proteoglycan circulating anodic antigen) was used.

A comparison of the IFA and the ELISA for the demonstration of antibodies against schistosome gut-associated polysaccharide antigens in schistosomiasis

The applicability of two immunodiagnostic techniques was studied for the detection of antibodies against schistosome gut-associated polysaccharide antigens in human schistosomiasis mansoni: the immunofluorescent antibody reaction (IFA) using Rossman's fixed paraffin sections of adult worms and the enzyme-linked immunosorbent assay (ELISA) with a trichloroacetic acid soluble fraction of total adult worm antigens (AWA-TCA). With the IFA, gut-associated polysaccharide antigens could be demonstrated with an anti-IgM conjugate in a high percentage of the sera tested, although false-negative reactions were occasionally recorded. The use of an anti-IgG conjugate resulted in the demonstration of antibodies against additional antigens in the parenchyma of the worm and on the tegument. Specific IgM antibodies were present in higher concentrations in the sera from children than in those from adults. Using AWA-TCA as the antigen preparation in the ELISA, only antibodies against the circulating anodic antigen (CAA) could be demonstrated. Pretreatment of the ELISA-plates with poly-L-lysine to couple AWA-TCA was not necessary. The ELISA was successfully applied with anti-Ig, anti IgG, and anti-IgM conjugates. With anti-Ig conjugate the test was very sensitive and gave less false-negative reactions than the IFA. There was a significant difference between Ig, IgG, and IgM titres of children and adults. The use of an immunogalactosidase assay with a fluorogenic substrate in the ELISA, resulted in a test which was able to detect antibodies at ten times higher dilutions than with the immunoperoxidase assay.

Detection of antibodies against circulating cathodic antigen of Schistosoma mansoni using the enzyme-linked immunosorbent assay

The applicability of a Schistosoma mansoni polysaccharide antigen, circulating cathodic antigen (CCA), for the detection of antibodies in S. mansoni infection was tested in the enzyme-linked immunosorbent assay (ELISA). Antibodies against this secretory antigen were detected in hamster infections after three weeks, while in infected humans anti-CCA antibodies could be demonstrated eight weeks after infection. Antibodies could be demonstrated both in recent and chronic infections in man, but more false-negative results were observed in chronic infections. The antibody response was composed of both IgM and IgG antibodies.

H-2 linked immune response to murine experimental Schistosoma mansoni infections

Mice of two congenic inbred strains C3H/Sn (H-2k) and C3H.B10 (H-2b) were infected with 100 Schistosoma mansoni cercariae. After the infection, the following parameters for the immunological response were studied: worm burden, mortality, antibody titre, spleen index, eosinophilia, delayed type of hypersensitivity and in vitro response to three S. mansoni antigen preparations. No difference in the worm burden and in the in vitro response to the antigen preparations of adult worm antigen, soluble egg antigens and the egg antigen MSA1, was found. The C3H.B10 mice showed a significantly higher mortality, antibody titre and delayed type of hypersensitivity while the C3H/Sn mice showed asignificantly higher spleen index and eosinophilia. This indicates that the H-2 region influences the course of an acute S. mansoni infection, whereas the susceptibility to the infection seems not to be influenced, as is shown by the worm burden.

Spontaneous glomerular basement membrane changes in the golden Syrian hamster (Mesocricetus auratus): a light and electron microscope study

Changes in apparently healthy hamsters, consistent with proteinuria, are reported, but no IgG deposits or amyloid in the glomeruli were detected. Further investigation is required into the significance and the aetiology of these, as yet, obscure alterations.

Class-specific antibody titres (ELISA) against the primary immunogen Helix pomatia haemocyanin (HPH) in man

Using the indirect ELISA technique, IgM, IgG and IgA antibody titres against the primary test immunogen Helix pomatia haemocyanin (HPH) could be measured. All twenty-seven normal volunteers (age range 26-74 years) developed maximal or high IgM, IgG and IgA antibody titres 2 weeks after primary immunization with 1.0 mg HPH subcutaneously. Lower dose immunization resulted in submaximal responses. Titre kinetics in the three Ig classes correlated in height and time per person. There was no significant difference in antibody response between two adult age groups. Secondary immunization after 6 weeks, again with 1.0 mg HPH, when high titres were still present, resulted in a small titre increase in all three Ig classes. Comparison with the tanned red cell agglutination technique used previously, in combination with the 2-mercaptoethanol treatment of sera, showed the unreliability of 7S titres measured thus early in the primary immune response. Investigation of four patients with humoral immunodeficiency confirmed the class specificity of the test.

An indirect haemagglutination reaction for the demonstration of Schistosoma mansoni circulating anodic antigen

Using the IgG fraction of a monospecific sheep antiserum against the circulating anodic antigen (CAA) of Schistosoma mansoni, an indirect haemagglutination reaction for the determination of this antigen was developed. This is the first time that an IHA has been applied to the detection of circulating antigens in parasite infections. The IHA proved to be highly sensitive; CAA levels up to 20 ng/ml could be measured. At the moment it appears to be the most sensitive technique for the determination of CAA levels. CAA could readily be detected in the sera of S. mansoni infected hamsters and in the immune complexes isolated from these sera, but never in sera from human schistosome infections.

Effect of partial portal vein ligation on immune glomerular deposits in Schistosoma mansoni-infected mice

Portosystemic collateral circulation was induced in mice infected or not with Schistosoma mansoni by partial ligation of the portal vein. The effects on immune glomerular deposits were assessed and compared to findings in unoperated infected, sham-operated and normal animals. Mesangial immune deposits of IgM, IgA, IgG and C3 were found by immunofluorescence significantly more frequently in operated than in unoperated infected mice. Schistosomal antigen was demonstrated in 5 animals out of 38 infected ones, 4 of the 5 having been operated. The results suggest that portosystemic collateral circulation might be an important factor in the genesis of schistosomal glomerulopathy, perhaps by diversion of antigens or complexes from the Kupffer cells. The high percentage of glomerular immune deposits found in uninfected ligated animals (71-4%) suggests furthermore that non-specific immune factors possibly of intestinal origin could be involved.

Immunodiagnosis of human schistosomiasis using different immunoprecipitation techniques

One hundred sera of individuals infected with Schistosoma mansoni and/or S. haematobium were examined for the presence of specific anti Schistosoma antibodies by means of different immunoprecipitation techniques: immunoelectrophoresis, immunodiffusion, immunoelectroosmophoresis (on two different supports), and electroimmunodiffusion. The immunoelectroosmophoresis proved to be superior to the other immunoprecipitation techniques, its main advantages being sensitivity, rapidity, and economic use of reagents. Precipitins against the antigen of the intermediate host, Biomphalaria glabrata, were demonstrated in 66% of the sera.

Antigen-coupled beads adherent to slides: a simplified method for immunological studies

Small amounts of antigen-coupled beads adherent to object slides provide a simple, quick, economical and sensitive immunohistochemical means of detecting antibodies in serum by both immunofluorescence and immunohistoperoxidase procedures. Sensitivity increases with decreasing quantities of antigen-coupled beads, as was demonstrated in the fluorescence procedure.

Immunoprecipitation and class-specific immunofluorescence titration of human serum antibodies to Schistosoma mansoni antigens

Twenty sera of individuals with Schistosoma mansoni infections were examined by means of immunoelectrophoresis, Indirect Flourescent Antibody (IFA) technique and the Defined Antigen Substrate Spheres (DASS) system. Immunoprecipitins against S. mansoni antigen and against antigen of the intermediate host, Biomphalaria glabrata, were demonstrated. The presence of specific anti-S. mansoni IgA, IgM, IgG and IgE antibodies were demonstrated. The presence of specific anti-S. MANSONI IgA, IgM, IgG and IgE antibodies was identified with the IFA-technique on frozen sections of adult parasites. The DASS-system proved to be more sensitive than the IFA-technique.

Serodiagnostic application of immunohistoperoxidase reactions on antigen-coupled agarose beads

Agarose beads to which antigens were covalently bound were subjected to indirect immunohistoperoxidase procedures. For detection and titration of serum antibodies against bovine gamma globulin (BGG) this method appeared to be specific and sensitive. One advantage is that no special instruments are needed. As an example of diagnostic applicability the system was successfully used for demonstration of antibodies in human serum containing antibodies against the trematode Schistosoma mansoni. At the microscopical level the technique is suitable for study of basic problems. Microspectrophotometric absorbance scanning of the beads revealed that the method can provide quantitative information, and is probably capable of quantifying stoichiometric relations in immunological reactions.