Early development and progression of lymphocyte-stimulatory cross-reactive idiotypes expressed on antibodies to soluble egg antigens during Schistosoma mansoni infection of mice

Idiotypes (Id) that stimulate immunoregulatory anti-Id T lymphocyte proliferation are expressed on murine and human antibodies (Ab) to soluble egg antigens (SEA) of Schistosoma mansoni. Kinetics of early expression of these stimulatory Id have now been studied using immunoaffinity-purified serum anti-SEA Ab from mice infected with S. mansoni for 6, 7, 8, 12, or 16 weeks. Rabbit anti-Id Ab specific for mouse anti-SEA Id expressed at 8 weeks post-infection (anti-8WkId) demonstrated the strongest interactions with Id present at 7 and 8 weeks post-infection by competitive enzyme-linked immunosorbent assay. Anti-8WkId Ab reacted progressively less well with 12 WkId, 6WkId, and 16WkId. Splenocytes from mice infected for 8 weeks demonstrated the highest blast transformation responses in vitro to anti-SEA Id from mice infected for 6 weeks, while 7, 8, 12, and 16 weeks post-infection Id preparations stimulated progressively less proliferation. These data indicate that although eventual Id-associated immunoregulatory events contribute to chronicity in this disease, production of anti-SEA Ab that express stimulatory cross-reactive immunoregulatory Id comprises a substantial portion of the initial, acute anti-SEA response in mice infected with Schistosoma mansoni. Furthermore, either this particular Id-expressing response is not maintained, or its proportional presence is greatly diminished by the cumulative production of other multiple anti-SEA Ab during the establishment of chronicity, perhaps in response to its immunoregulatory influence very early in infection.     

The Th1 to Th2 shift induced by Schistosoma mansoni does not exacerbate murine aids (MAIDS)

Schistosoma mansoni infection in mice is associated with a switch from a Th1 to a Th2-type cytokine response. The role of Th1 and Th2 responses in immune dysregulations associated with AIDS and murine AIDS (MAIDS) is controversial, but a Th2 bias could be associated with disease progression, raising the hypothesis that helminth infections might accelerate the retroviral disease progression. Here, we used the murine model of AIDS to evaluate the course of the viral disease during co-infection with S. mansoni. C57BL/6 mice were infected with S. mansoni cercariae 8 weeks before intravenous challenge with the LP-BM5 retroviral complex. MAIDS did not progress faster in co-infected mice, in terms of spleen and inguinal lymphadenopathy size, ecotropic virus titres in the spleen, or in vitro proliferative responses to mitogen. Th2 cytokine production was not enhanced in co-infected animals, except for an isolated increase in IL-4 production 21 weeks after LP-BM5 infection. Co-infected animals had significantly lower lymph node and spleen weights than mice infected with LP-BM5 only. MAIDS did not influence the granulomatous response to S. mansoni in the liver of co-infected mice. Finally, infection with S. mansoni neither enhanced Th2 cytokine production nor accelerated MAIDS progression in animals subsequently challenged with LP-BM5.     

Effect of Schistosoma mansoni infection on offsprings born from infected mothers

Offsprings C57BL/6 mice (4 weeks old) coming from either moderately infected (40 S. mansoni cercariae) or heavily infected (100 S. mansoni cerariae) mothers, were exposed to 40 S. mansoni cercariae each. Seven weeks post infection (P.I.), Offsprings were sacrificed. In both groups there was significant reduction in the worm load, both hepatic and intestinal tissue egg count. The oogram profile was not altered. Humoral immune response as regards the level of anti S. mansoni SEA Ab was elevated in both groups in comparison to their parallel controls at 2 weeks post delivery and 7 weeks P.I. The level of antibodies was significantly higher in heavily infected Offsprings than that present in offsprings coming from moderately infected mothers. Delayed footpad swelling and hepatic granuloma size were significantly reduced in both groups comparing with their corresponding controls.     

Biology and pathology of Schistosoma mansoni and Schistosoma japonicum infections in several strains of nude mice

Schistosoma mansoni and S. japonicum infections in nude mice (nu/nu) were compared with infections in nu/+ heterozygotes or intact mice. Seven to 12 weeks after exposure to S. mansoni, the responses of Swiss NCR, C3H, BALB/c and C57B1/6 nude mice did not differ substantially. Nude mice of all these strains showed minute granulomas around eggs in the liver and minimal hepatic fibrosis. Microvesicular and necrotizing changes in hepatocytes were similar in all mouse strains, and S. mansoni infections were frequently lethal to nude, but not to intact mice between the seventh and ninth weeks of infection. Nude mice that survived the ninth week of infection generally lived until the 12th week. The number of eggs per mature worm pair in the tissues of S. mansoni-infected nude mice was similar to the number in intact mice, but nude mice passed fewer eggs in the feces. Nude mice that received serum from infected intact mice excreted eggs in the stool in numbers equivalent to intact mice, but continued to form minute granulomas around S. mansoni eggs. Reconstitution with fetal thymus or with splenocytes from normal or S. mansoni-infected mice partially or completely restored hepatic granuloma size, granuloma eosinophils, hepatic fibrosis, and excretion of eggs in the feces. In contrast to S. mansoni infection, S. japonicum infections in nude mice did not cause necrosis of hepatocytes or excessive mortality, and S. japonicum eggs were passed in the feces in numbers equivalent to those passed by infected intact mice.     

Anti-schistosomal IgE and its relation to gastrointestinal allergy in breast-fed infants of Schistosoma mansoni infected mothers

To study the relationship between presence of gastrointestinal allergic manifestations in breast-fed infants and presence of IgE against Schistosoma mansoni antigens, sixty breast-fed infants of S. mansoni infected mothers were selected. Of them, thirty infants were suffering from manifestations of gastrointestinal allergy (patients) and the other thirty were not suffering from such manifestations (controls). Levels of IgE against S. mansoni adult worm antigen (AWA), soluble egg antigen (SEA) and cercarial antigen (CA) were determined, by ELISA, in sera of these infants. There was significant association between presence of allergic manifestations and presence of IgE against AWA (P = 0.018), SEA (P < 0.001) and CA (P = 0.002). Also, concentration of IgE against AWA was significantly higher in patients group than the control group (P = 0.024). IgE against AWA showed significant negative correlation with haemoglobin concentration (P = 0.009) and serum albumin level (P = 021) and significant positive correlation with absolute eosinophilic count (P = 0.005). Also, IgE against CA showed significant negative correlation with haemoglobin concentration (p = 0.047) and serum albumin level (0 = 0.036). It was concluded that gastrointestinal allergy in breast-fed infants of S. mansoni infected mothers may be due to hypersensitivity of Schistosoma mansoni antigens present in mothers' milk. Schistosoma mansoni should be investigated and treated in mothers from endemic localities when their breast-fed infants are suffering from manifestations suggestive of gastrointestinal allergy.     

Inhibition of lymphocyte proliferation by factor(s) produced by Schistosoma mansoni

Normal spleen cells of CBA mice or Fischer rats were cultured with mitogens or allogeneic cells, together with various substances of Schistosoma mansoni origin, and thymidine uptake was measured. The proliferation (DNA synthesis) of normal lymphocytes was inhibited by the incubation product of the parasite as well as by cell-free supernatant of schistosome culture. Inhibition was obtained only when active materials were added at the beginning of the culture. Both T and B cell proliferation were inhibited. The inhibitory activity found in cell-free supernatant suggested the release by the parasite of some factor(s) interfering with lymphocyte proliferation. Moreover, serum from rats infected by S. mansoni inhibited lymphocyte proliferation also. The inhibitor(s) appeared heat resistant, dialyzable and of low molecular weight (500-1000). Incubation of normal spleen cells with S. mansoni inhibitor(s) did not enhance the release of nonspecific suppressor cell factor. The inhibition of product(s) released by the parasite could explain part of the immunosuppression status found in schistosomiasis.     

Antibodies reactive to Trypanosoma cruzi epimastigotes or amastigotes express different idiotypic patterns if from patients with different clinical forms of Chagas' disease

Antibodies (Abs) were purified from pooled sera of patients with either indeterminate (IND or I) or cardiac (CARD or C) Chagas' disease, on either epimastigote (EPI or E) or amastigote-enriched (AMAST or A) antigen (Ag) columns and their idiotypic (Id) expression examined. Anti-Id rabbit Abs were raised to the different preparations (E-IdI, E-IdC, A-IdI and A-IdC). Competitive ELISAs using anti-Ids were able to discriminate between IdI and IdC, disregarding Ag reactivity. E-IdI and A-IdI present different inhibitory abilities, as do E-IdC and A-IdC, but IdC always competes with IdI for anti-IdI comparably. In contrast, a 4-8-fold increase of IdI is required to compete in parallel with IdC for anti-IdC. Therefore, Ids from IND patients share only low levels of the Ids that are most characteristic of CARD patients. While some CARD Abs also express Ids in common with IND patients, these studies reveal that CARD Abs express some Ids that are characteristic to only CARD patients, and these Ids are present on Abs purified with either EPI or AMAST.     

The role of host (endogenous) T cells in chronic graft-versus-host autoimmune disease

Chronic graft-vs-host (cGVH) disease induced by the transfer of Ia-incompatible spleen cells from one normal mouse strain (such as B6.C-H2(bm12)/KhEg (bm12)) to another (such as C57BL/6) causes an autoimmune syndrome resembling systemic lupus erythematosus (SLE). The role of host-derived T cells in this response is not obvious. Previous reports suggested that host T cells might serve to down-regulate the autoimmune syndrome. To address this issue more definitively, we used CD4 knockout (KO) or CD8KO C57BL/6 (B6) mice as recipients in the bm12-->C57B6 cGVH model. CD4KO B6 mice injected with allogeneic bm12 spleen cells (bm12-->CD4KO group) showed no evidence of cGVH disease. They made no detectable autoantibodies, including anti-chromatin, anti-dsDNA, anti-ssDNA, and rheumatoid factor. They survived at least 20 wks after induction of cGVH disease; and they did not develop nephritis, based on the absence of detectable levels of proteinuria and normal renal histology at the time of sacrifice. By contrast, CD8KO B6 mice (bm12-->CD8KO group) and normal B6 mice (bm12-->B6 group) injected with bm12 spleen cells generally showed similar levels of mortality, nephritis, and autoantibodies, although the autoantibody titers declined somewhat after week 8 in the bm12-->CD8KO group. Control groups of recipients injected with B6 spleen cells showed no induction of autoantibodies. A surprising finding, however, was that the B6-->CD8KO group developed severe histologic glomerulonephritis in the absence of autoantibodies and with decreased immune deposits. These results indicate that endogenous (host) CD4+ T cells play an essential role in the cGVH autoimmune syndrome.     

Fc epsilon receptor-positive cells are a major source of antigen-induced interleukin-4 in spleens of mice infected with Schistosoma mansoni

When cultured in vitro with either mitogen or parasite antigens, spleen cells from mice infected with Schistosoma mansoni produce significantly higher levels of IL-4 than splenocytes from control animals. Previous studies suggested that this increase in IL-4 production occurs because of a selective expansion of T helper type 2 (Th2) cells in infected mice. However, these experiments employed unfractionated spleen populations rather than purified T lymphocytes. Here we demonstrate that T-depleted spleen cells from infected animals synthesize high levels of interleukin-4 (IL-4), but no IL-5 when stimulated with parasite antigen in vitro. Nevertheless, when purified by sorting, T cells and non-B, non-T (NBNT) populations produced similar amounts of IL-4 in response to parasite antigen. The IL-4 producing NBNT cells were found to belong to an Fc epsilon receptor (Fc epsilon R)-positive population which after sort purification produced high levels of IL-4 (between 1000 and 2000 U of per 5 x 10(3) cells). FACS analysis revealed that these Fc epsilon R+ cells make up 0.53% of splenic NBNT cells in control animals while in 8-9-week-infected animals they increase to 3.8% of that population. In contrast, in mice with 8-week unisexual worm infections these cells comprise only 1.71% of NBNT cells, indicating that eggs are a major stimulus of the response. The expansion of Fc epsilon R+ cells and their production of IL-4 could be an important factor regulating the selection and induction of different CD4+ subsets in schistosome-infected hosts.     

Successful immunotherapy of the highly metastatic murine ESb lymphoma with sensitized CD8+ T cells and IFN-alpha/beta

Daily IFN-alpha/beta therapy was totally ineffective in inhibiting the development of visceral metastases in DBA/2 mice injected i.v. with the ESb lymphoma regardless of the number of tumor cells injected. The finding that IFN-alpha/beta therapy increased the survival time of ESb-immunized mice rechallenged with ESb cells suggested that cooperation between the immune system and IFN-alpha/beta was important. Adoptive transfer of Esb-immune spleen cells (but not normal cells) together with IFN-alpha/beta treatment did inhibit the development of ESb metastases in immunocompetent DBA/2 mice. Either treatment alone was ineffective. The anti-metastatic effect was specific for the ESb lymphoma as spleen cells from ESb-immunized mice together with IFN-alpha/beta treatment did not inhibit the development of metastases in mice challenged with IFN-alpha/beta-resistant 3C18 FLC. Depletion of CD8+ T cells (but not CD4+ T cells or B lymphocytes) prior to transfer eliminated the protective effect of ESb-immune splenocytes in IFN-alpha/beta-treated mice. As few as 1 x 10(6) ESb-immune spleen cells highly enriched for CD8+ cells increased the survival time of IFN-alpha/beta-treated ESb-challenged DBA/2 mice. The combined therapy of ESb-specific immune cells and IFN-alpha/beta resulted in long-term immunity to this tumor.     

Tegument changes of Schistosoma japonicum and Schistosoma mansoni in mice treated with artemether

AIM: To study the effect of artemether (Art) on the tegument of schistosomes. METHODS: Mice infected with S japonicum cercariae for 7 and 35 d, or with S mansoni cercariae for 49 d were treated intragastrically with Art 200-300 mg.kg-1.d-1 for 2 d. Schistosomes were collected in groups of 2 mice at various intervals after medication for scanning electron microscopic observation. RESULTS: The tegumental changes induced by Art appeared to be similar in S japonicum and S mansoni: swelling and fusion of tegumental surfaces, vesicle formation and collapse of discoid-like sensory structures. In S japonicum the emergence of tegumental alterations was earlier in 7-d-old schistosomulae than that in 35-d-old adult worms. CONCLUSION: Art injured the teguments of S japonicum and S mansoni.     

Profound deletion of mature T cells in vivo by chronic exposure to exogenous superantigen

It has been noted previously that superantigens can under different circumstances stimulate activation, expansion, anergy, and/or deletion of reactive T cells in vivo and in vitro. Here, we present a detailed examination of the expansion and deletion of T cells in vivo in response to the superantigens staphylococcal enterotoxin A (SEA) in the B10.BR mouse. Mice were either acutely or chronically exposed to varying doses of SEA, and the relative level of T cells bearing SEA-reactive V beta elements was followed over time in lymphocytes purified from peripheral blood, lymph nodes, mesenteric lymph nodes, and spleen. In most cases, an initial sharp rise in the proportion of reactive T cells was followed by a dramatic decline. Cells of the CD4+ and CD8+ lineages displayed subtle differences in their kinetics of activation and deletion, as well as their sensitivity to different doses of SEA. Furthermore, cells bearing either of two V beta elements previously characterized as SEA-reactive showed some differences in their responses to SEA treatment. Acute exposure usually caused the disappearance of only 50% to 70% of reactive T cells; however, chronic exposure to SEA caused almost complete deletion of target T cells. Deletion was evident even in animals treated with very low doses of SEA, doses that were too small to cause any apparent T cell proliferation. Thus, proliferation does not appear to be a prerequisite for peripheral deletion of T cells.     

Induction of cellular and humoral immunological responsiveness to a soluble cercarial antigen preparation from Schistosoma mansoni

Intradermal testing was performed with a soluble cercarial antigenic preparation (CAP) from Schistosoma mansoni cercariae in CBA/J mice multiply infected with S. mansoni or sensitized with CAP. Both an early (5-h) response and a late (24- to 48-h) reaction to CAP, as measured by increase in dermal thickness, was elicited after injection of antigen into the ears of either multiply infected (3X-75) or CAP-sensitized (CAP/complete Freund adjuvant [CFA]) mice. Histopathological examination showed that the early response was primarily vascular in nature and involved a polymorphonuclear cell infiltrate in and around dilated capillaries. The late reaction to CAP consisted of a perivascular cellular infiltrate of polymorphonuclear and mononuclear cell types. Passive transfer of 3X-75-infected or CAP/CFA-sensitized serum (0.4 ml) to normal mice conveyed the ability to mount an early (5-h) response to CAP which was marked histopathologically by a prominent polymorphonuclear cell infiltrate. The majority of the responsiveness in normal mice after administration of lymph node cells (40 X 10(6)) from multiply infected or CAP/CFA-sensitized mice was observed 24 to 48 h after injection of CAP and was mononuclear in nature.     

Evaluation of the humoral immune response of CD rats following a 2-week exposure to the pesticide carbaryl by the oral, dermal, or inhalation routes

The objective of this study was to examine the immunotoxicological effects of the methyl-carbamate pesticide carbaryl via the oral, dermal, or inhalation routes. Male CD rats were exposed to carbaryl 5 d/wk for a 2-wk period. During nose-only inhalation exposures, rats received either 36, 137, or 335 mg/m3 carbaryl in acetone for 6 h. Air only and acetone/air controls were run concurrently. Orally exposed animals received either 1 ml corn oil or 10, 25, or 50 mg/kg carbaryl, while dermally exposed animals received either 2 ml acetone or 100, 500, or 1000 mg/kg carbaryl on their dorsal flank for 6 h. Four days prior to sacrifice, animals from all exposure groups were injected iv with 2 x 10(8) sheep red blood cells (SRBC). The primary immunoglobulin M (IgM) humoral immune response to SRBC was then assessed by measuring SRBC-specific antibody-forming cells (AFC) and levels of serum anti-SRBC IgM antibody, respectively, using the hemolytic plaque assay and an enzyme-linked immunosorbent assay. Individual body weights, spleen, thymus, and liver weights, spleen cell number, and red and white blood cell (RBC, WBC) counts were obtained for each animal. Following nose-only inhalation exposures, dose-dependent decreases in thymus weights, spleen cell number, AFC/spleen, AFC/10(6) splenocytes, and serum levels of SRBC-specific IgM antibody were observed. Significant decreases of 33, 57, and 22% in spleen cell number, AFC/spleen, and thymus weight, respectively, were found at the 335 mg/m3 exposure level. Animals exposed orally to 25 mg/kg carbaryl had a 34% decrease in WBC counts. A 34% decrease in WBC and a 13% increase in RBC counts were observed at the 50 mg/kg oral dose. Significant decreases in liver weights ranging from 11 to 13% were found at all oral exposure levels. Dermal exposure to carbaryl revealed no significant toxicological effects. Results indicate that humoral immune suppression was observed following inhalation, but not following oral or dermal exposures to carbaryl. Immunotoxicological studies evaluating pesticides need to consider relevant exposure routes and dosages for appropriate risk assessment procedures and exposure limits to be established.     

Influence of dopamine on GABA release in striatum: evidence for D1-D2 interactions and non-synaptic influences

Serum samples of mice infected with 80 cercariae of Schistosoma mansoni for different time periods (2-20 weeks) were used in this study. It was observed that the concentrations of serum total cholesterol and triacylglycerol decreased significantly (P < 0.001, P < 0.0001 respectively) in infected as compared to control mice starting from the fourth week post infection. Similarly, the concentration of serum high density lipoprotein-cholesterol (HDL-C) decreased significantly (P > 0.001) in infected as compared to control mice. However, the serum lipoproteins profile was variable at different stages of infection. On the other hand, the liver weight increased significantly (P < 0.0001) in infected as compared to control mice starting from the sixth week post infection. These changes might be attributed to several metabolites released by S. mansoni which affect the host hepatic tissue resulting in decreased synthesis of these parameters and their release into the circulation.     

Laboratory assessment of the molluscicidal and cercaricidal activities of the Egyptian weed, Solanum nigrum L

The molluscicidal properties of Solanum nigrum L. were tested against three Egyptian snail species (Biomphalaria alexandrina, Bulinus truncatus and Lymnaea natalensis), each an intermediate host of parasites causing human schistosomiasis or fascioliasis. The plant was collected in two regions within Egypt: Fayium and Giza. Snails were exposed for 24 and 48 h, to the dry powdered fruits and leaves or to crude water extracts of the powders, and mortality was recorded. The water extract of the leaves collected in Fayium (FLWE) had the highest molluscicidal activity, with median lethal concentrations (LC50) of 18.6 mg/litre for Bi. alexandrina, 14.5 mg/litre for Bu. truncatus and 17.7 mg/litre for L. natalensis. When Bi. alexandrina infected with Schistosoma mansoni were exposed to FLWE (20 or 25 mg/litre), they shed significantly fewer cercariae than unexposed snails (P < 0.02). The cercaricidal properties of FLWE were directly tested against S. haematobium, S. mansoni and Fasciola gigantica cercariae and a time-concentration relationship was observed; the concentrations needed to kill all cercariae (LC100) within 30 min of exposure were 30 mg/litre for both S. haematobium and S. mansoni and 40 mg/litre for F. gigantica.     

Mice deficient for 5-lipoxygenase, but not leukocyte-type 12-lipoxygenase, display altered immune responses during infection with Schistosoma mansoni

Periovular granuloma formation during Schistosoma mansoni infection is a complex, multifaceted immunologic response. Products of arachidonic acid metabolism have been shown to contribute to this response through studies in which general inhibitors of lipoxygenase function reduce granulomatous inflammation. To determine which lipoxygenases are important for granuloma development in schistosomiasis, wild type mice or mice deficient for 5-lipoxygenase (5-LO) or "leukocyte-type" 12-lipoxygenase (12-LO) were infected with S. mansoni and studied for responses to schistosome eggs and egg antigens. At the acute stage of infection, when granuloma formation is usually maximal, 5-LO deficient mice developed smaller granulomas around liver-deposited schistosome eggs compared with wild type or 12-LO deficient mice. 5-LO mice also displayed less antibody-mediated (5 h) and cell-mediated, delayed-type (24 h) hypersensitivity to schistosome egg antigens than did the other two infection groups. In an attempt to determine possible mechanisms for the reduced inflammatory responses, we also measured hepatic mRNA levels of cytokines that have been shown to influence granuloma size (IL-4, IL-10, and IFN-gamma). The mRNA levels for IL-10 were significantly lower in 5-LO-deficient mice, but SEA-stimulated spleen cells did not demonstrate a significant difference in IL-10 production between wild type and 5-LO mice. These data suggest that 5-LO plays a role in host responses to schistosomiasis via a mechanism that cannot be explained solely by changes in expression of these cytokines.     

Some genetic, clinical and immunologic interrelations in schistosomiasis mansoni

The aim of the present work was to study the possible association of some class I, II MHC gene products with variations in the clinico-pathological outcome of human schistosomiasis mansoni as well as with the variability in immune responsiveness. The study was carried out on 47 patients with schistosomiasis mansoni and 20 healthy volunteers served as control group for the immunological parameters and 200 subjects for the genetic studies. The following were determined: class I, II HLA typing, serum IgG, IgM, C3c, immediate intradermal test and passive haemagglutination using S mansoni worm antigen, T lymphocyte subsets, delayed intradermal test and leukocyte migration inhibition using phytohaemagglutinin (PHA) and soluble egg antigen (SEA) of S mansoni. A statistically significant association was found between HLA-B5 and DR3 and with the occurrence of hepatosplenic disease; this phenotype also correlated with changes in T lymphocyte subsets and high immune reactivity, both humoral and cell mediated. HLA-DQI was also associated with failure to develop hepatosplenic disease. The present study consolidates also the view of the important role of host immune reactivity in the clinical outcome of schistosomiasis mansoni and demonstrates the contribution of the genetic impact on both clinical and immunological heterogeneity of the disease.     

Studies on experimental mixed infection of Schistosoma haematobium and Schistosoma mansoni

Swiss Albino mice have been infected with S. haematobium and challenged 4 weeks later with S. mansoni. Parasitological, pathological and ultrastructural studies were done. The results revealed cross mating between the two species. A reduction in S. mansoni worm load, egg count, hepatic granuloma number and size was noticed. The presence of heterologous immunity was suggested.