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E Claassen

Publications and source records attributed to E Claassen.

At least 19 recordsLinked to original sources
PubMed2003

How does Trypanosoma equiperdum fit into the Trypanozoon group? A cluster analysis by RAPD and multiplex-endonuclease genotyping approach.

The pathogenic trypanosomes Trypanosoma equiperdum, T. evansi as well as T. brucei are morphologically identical. In horses, these parasites are considered to cause respectively dourine, surra and nagana. Previous molecular attempts to differentiate these species were not successful for T. evansi and T. equiperdum; only T. b. brucei could be differentiated to a certain extent. In this study we analysed 10 T. equiperdum, 8 T. evansi and 4 T. b. brucei using Random Amplified Polymorphic DNA (RAPD) and multiplex-endonuclease fingerprinting, a modified AFLP technique. The results obtained confirm the homogeneity of the T. evansi group tested. The T. b. brucei clustered out in a heterogenous group. For T. equiperdum the situation is more complex: 8 out of 10 T. equiperdum clustered together with the T. evansi group, while 2 T. equiperdum strains were more related to T. b. brucei. Hence, 2 hypotheses can be formulated: (1) only 2 T. equiperdum strains are genuine T. equiperdum causing dourine; all other T. equiperdum strains actually are T. evansi causing surra or (2) T. equiperdum does not exist at all. In that case, the different clinical outcome of horse infections with T. evansi or T. b. brucei is primarily related to the host immune response.

Animals↗
PubMed2003

Enhanced immunological memory responses to Listeria monocytogenes in rodents, as measured by delayed-type hypersensitivity (DTH), adoptive transfer of DTH, and protective immunity, following Lactobacillus casei Shirota ingestion.

We have investigated the effect of orally administered Lactobacillus casei Shirota (L. casei) on immunological memory, as measured by delayed-type hypersensitivity (DTH) and acquired cellular resistance (ACR). The studies were performed in animal models in which the animals were rendered immune by a primary Listeria monocytogenes infection. It was shown that orally administered viable L. casei, and not heat-killed L. casei, enhanced significantly the antigen-specific DTH at 24 and 48 h in Wistar rats, Brown Norway rats, and BALB/c mice in a time- and dose-dependent fashion. L. casei had to be administered at least 3 days prior to the DTH assay at a daily dose of 10(9) CFU in order to induce significant effects. Long-term administration of 10(9) CFU of viable L. casei resulted in enhanced ACR, as demonstrated by reduced L. monocytogenes counts in the spleen and liver and diminished serum alanine aminotransferase activity after reinfection. Enhancement of cell-mediated immunological immune responses by L. casei was further established in an adoptive transfer study. Naïve recipient BALB/c mice, which were infused with nonadherent, immunized spleen cells from L. casei-fed donor BALB/c mice, showed significantly enhanced DTH responses at 24 and 48 h compared to recipient mice which received spleen cells from control donor mice. In conclusion, orally administered L. casei enhanced cell-mediated immunological memory responses. The effects relied on lactobacillus dose and viability as well as timing of supplementation and, further, appeared to be independent of host species or genetic background.

Administration, Oral↗
PubMed2002

Modulation of delayed-type hypersensitivity and acquired cellular resistance by orally administered viable indigenous lactobacilli in Listeria monocytogenes infected Wistar rats.

AIMS: Various probiotic lactobacilli have been reported to modulate immunity. In this study we investigate the effects of viable indigenous Lactobacillus strains Utr-1, Utr-2 and Utr-3, on T cell-mediated immunological memory responses. METHODS AND RESULTS: In Listeria monocytogenes infected rats it was demonstrated that short-term daily ingestion of Lactobacillus strain Utr-3 significantly decreased delayed-type hypersensitivity (DTH) expression, whereas long-term, daily oral administration of Lactobacillus strain Utr-3 and Lactobacillus strain Utr-2 significantly enhanced acquired cellular resistance (ACR) towards Listeria re-infection. CONCLUSIONS: Our findings demonstrate that certain indigenous Lactobacillus strains are capable of modulating T cell-mediated immunity. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results support the importance of indigenous microflora analysis in probiotic lactobacilli studies.

Administration, Oral↗
PubMed2001

Alveolar macrophages, surfactant lipids, and surfactant protein B regulate the induction of immune responses via the airways.

The influences of alveolar macrophages (AM) and pulmonary surfactant on the induction of immune responses via the airways were assessed. Mice were depleted of their AM by intratracheal instillation of multilamellar vesicles containing dichloromethylene-diphosphonate followed by intratracheal instillation of a T cell--dependent antigen, trinitrophenyl--keyhole limpet hemocyanin, in vesicles of various compositions. The primary immune response was determined in the spleen of these animals using an ELI-Spot assay. The secondary immune responses in the sera of the mice were assessed using enzyme-linked immunosorbent assays. An immune response was detected in animals depleted of their AM and intratracheally instilled with antigen in small unilamellar vesicles consisting of either phosphatidylcholine cholesterol or surfactant lipids. Incorporation of surfactant protein (SP)-B in the antigen vesicles enhanced the immune response, whereas SP-A or SP-C in the antigen vesicle did not have an effect. Strikingly, intratracheal instillation of SP-B containing antigen vesicles can induce an immunoglobulin M immune response in mice without depletion of AM. These results indicate that SP-B containing vesicles can enhance the induction of immune responses via the airways and further illustrate the important roles of both AM and pulmonary surfactant in the pulmonary immune system.

Animals↗
PubMed2000

Strain-dependent induction of cytokine profiles in the gut by orally administered Lactobacillus strains.

Different Lactobacillus strains are frequently used in consumer food products. In addition, recombinant lactobacilli which contain novel expression vectors can now be used in immunotherapeutic applications such as oral vaccination strategies and in T cell tolerance induction approaches for autoimmune disease. Both for food and clinical applications of lactobacilli, proper selection of wild type strains is crucial. For that purpose, eight different common Lactobacillus strains were analysed with respect to mucosal induction of pro- and anti-inflammatory cytokines, IgA-producing plasma cells in the gut, as well as systemic antibody responses against a parenterally administered antigen. Immunohistochemical analysis of cytokine-producing cells in the gut villi showed no significant induction of the cytokines IL-1alpha, IFN-gamma, IL-4 or IL-10 after oral administration of wild type Lactobacillus strains. In contrast, oral administration of L. reuteri and L. brevis induced expression of the proinflammatory/Th1 cytokines TNF-alpha, IL-2 and/or IL-1beta. Oral administration of these two strains and L. fermentum also significantly enhanced the IgG response against parenterally administered haptenated chicken gamma globulin (TNP-CGG). The five other strains did not show this adjuvanticity. L. reuteri induced relatively high levels of IgG2a compared to L. murines, a nonadjuving Lactobacillus strain. These findings imply that different Lactobacillus strains induce distinct mucosal cytokine profiles and possess differential intrinsic adjuvanticity. This suggests that rational Lactobacillus strain selection provides a strategy to influence cytokine expression and thereby influence immune responses.

Adjuvants, Immunologic↗
PubMed2000

Abundant expression of CD40 and CD40-ligand (CD154) in paediatric Langerhans cell histiocytosis lesions.

The pathogenesis of Langerhans cell histiocytosis (LCH) is obscure, partly because the events leading to activation of Langerhans-like lesional cells (LCH cells) and associated T cells, and the excessive cytokine production by these cells are unknown. The interaction between CD40 on antigen-presenting cells (APC) like Langerhans cells and CD40 ligand (CD40L) (CD154) expressed by activated CD4+ T cells, is essential for the activation of both the APC and the T cells and results in upregulation of APC functions and initiation of immunoreactivity. The effects of CD40-CD40L interaction include increased expression of co-stimulatory and adhesion molecules, proliferation, and production of pro-inflammatory cytokines and proteolytic enzymes, all features of LCH. Using immunohistochemistry, we analysed the in situ presence of the co-stimulatory molecules CD40 and CD40L in 15 fresh frozen biopsies of LCH lesions in children. The cells producing these molecules were identified by double staining for CD1a on LCH cells and CD3 on T cells. Prominent expression of CD40 by LCH cells and CD40L by T cells was found in all 15 specimens regardless of the source of specimen or characteristics of the patient. The findings of high expression of CD40 and CD40L in all specimens imply a key role for the CD40-CD40L adhesion pathway in the pathogenesis of LCH. Since this interaction is an accessible and realistic target for immunotherapy, these findings prompt speculation on the use of blocking antibodies to CD40 or to CD40L in the treatment of LCH.

CD40 Antigens↗
PubMed2000

An approach to the control of disease transmission in pig-to-human xenotransplantation.

Although several major immunologic hurdles need to be overcome, the pig is currently considered the most likely source animal of cells, tissues and organs for transplantation into humans. Concerns have been raised with regard to the potential for the transfer of infectious agents with the transplanted organ to the human recipient. This risk is perceived to be increased as it is likely that the patient will be iatrogenically immunocompromised and the organ-source pig may be genetically engineered in such a way to render its organs particularly susceptible to infection with human viruses. Furthermore, the risk may not be restricted to the recipient, but may have consequences for the health of others in the community. The identification of porcine endogenous retroviruses and of hitherto unknown viruses have given rise to the most concern. We document here the agents we believe should be excluded from the organ-source pigs. We discuss the likelihood of achieving this aim and outline the potential means by which it may best be achieved.

Animals↗
PubMed1999

Differential In situ cytokine profiles of Langerhans-like cells and T cells in Langerhans cell histiocytosis: abundant expression of cytokines relevant to disease and treatment.

The pathogenesis of Langerhans cell histiocytosis (LCH) remains poorly understood. To further elucidate LCH pathogenesis, we analyzed the expression of 10 cytokines relevant to cellular recruitment and activation at the protein level in 14 patients and identified the lesional cells responsible for cytokine production in situ by immunohistochemistry. The cytokines investigated included the hematopoietic growth factors interleukin-3 (IL-3), IL-7, and granulocyte-macrophage colony-stimulating factor (GM-CSF); the lymphocyte regulatory cytokines IL-2, IL-4, and IL-10; the inflammatory regulators IL-1alpha and tumor necrosis factor-alpha (TNF-alpha); and the effector cell-activating cytokines IL-5 and interferon-gamma (IFN-gamma). In all specimens, CD1a(+) histiocytes (LCH cells) and CD3(+) T cells produced large amounts of cytokines, creating a true cytokine storm. IL-2, IL-4, IL-5, and TNF-alpha were produced exclusively by T cells, whereas only IL-1alpha was produced by LCH cells. Equal numbers of LCH cells, T cells, and macrophages produced GM-CSF and IFN-gamma. Equal numbers of LCH cells and macrophages produced IL-10, whereas IL-3 was produced by T cells and macrophages. IL-7 was only produced by macrophages. Eosinophils, present in some specimens, were partially responsible for the production of IL-5, IFN-gamma, GM-CSF, IL-10, IL-3, and IL-7. Expression of all cytokines, abundant in most biopsies, was irrespective of age, gender, or site of biopsy. These findings emphasize the role of T cells in LCH. The juxtaposition of T cells and LCH cells suggests that both cells interact in a cytokine amplification cascade, resulting from stimulation of autocrine and paracrine stimulatory loops. This cascade can be linked directly to the development of LCH through recruitment, maturation, and proliferation of LCH cells. The cytokines studied are known to be involved in the development of other characteristic features of LCH, such as fibrosis, necrosis, and osteolysis.

Cells, Cultured↗
PubMed1999

FISH and CHIPs.

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Animal Diseases↗
PubMed1998

Expression of accessory molecules and cytokines in acute EAE in marmoset monkeys (Callithrix jacchus).

Accessory molecules and cytokines are involved in the immunopathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) in rodent models, and are potential targets for immunotherapy. Evaluation of such experimental therapies requires appropriate animal models. Therefore, we analysed the expression of selected accessory molecules and cytokines in the brain of marmoset monkeys (Callithrix jacchus) with acute EAE, a newly described non-human primate model for MS. All animals experienced active disease clinically and histopathologically with strong resemblance to MS. Perivascular infiltrates of mononuclear cells showed abundant expression of CD40. CD40 was expressed on macrophages, indicating that T cell priming and macrophage effector functions may result from local CD40-CD40L interactions. CD40 ligand (CD40L) and B7-2 (CD86) were also expressed, but to a lower extent, while B7-1 (CD80) expression was limited. Both pro-inflammatory and anti-inflammatory cytokines were produced within individual lesions during active disease (IFN-alpha, IFN-gamma, TNF-alpha, IL-1alpha, IL-1beta, IL-2, IL-4, IL-10 and IL-12). This suggests that relative levels rather than sequential expression of Th1- and Th2-type cytokines determine disease activity. These findings demonstrate the value of EAE in marmoset monkeys as a model to assess the role of accessory molecules and cytokines in multiple sclerosis, and to evaluate targeted intervention.

Acid Phosphatase↗
PubMed1998

Immune responses and side effects of five different oil-based adjuvants in mice.

In this study, five different oil based adjuvants were compared to assess efficacy and side effects. Mice were injected subcutaneously (s.c.) or intraperitoneally (i.p.) with a weak immunogen (synthetic peptide) emulsified in Freund's adjuvant (FA), Specol, RIBI, TiterMax or Montanide ISA50. Efficacy of adjuvants was evaluated based on their properties to induce peptide specific IgG1, IgG2a and total IgG antibodies, native protein cross-reactive antibodies and cytokine production. Side effects were evaluated based on clinical and behavioural abnormalities, and (histo)pathological changes. Although marked differences in isotype profile and height of titre are observed among the different adjuvants used, we found that FA, Montanide ISA50 and Specol worked equally well in the s.c. and i.p. route, TiterMax functioned only when given i.p. and RIBI also did not perform up to par. The number of cytokine (interferon-gamma and interleukin-4) producing spleen cells was significantly higher after injection of RIBI compared with other adjuvants. Injection of FA or TiterMax resulted in severe pathological changes while after RIBI injection minimal changes were observed. In conclusion, high peptide specific antibody levels with limited side effects can be obtained by s.c. injection of peptide combined with Montanide ISA50 or Specol as alternatives to FA.

Adjuvants, Immunologic↗
PubMed1998

Inadequate anti-polysaccharide antibody responses in the chicken.

Chickens are notorious for the fact that they carry bacteria such as Salmonellae and Campylobacter, which can cause zoonoses by contamination of the end product, without hampering growth and development of the chicken itself. This carrier status can only been explained by the inability of the chickens immune system to eliminate the pathogen, this in turn being due to insufficient humoral responses towards the polysaccharides of the bacterial capsule. In a previous study, we demonstrated that in chickens a model thymus-independent type 2 (TI-2) polysaccharide antigen, trinitrophenylated Ficoll (TNP-Ficoll), hardly evokes a humoral immune response. Furthermore this TI-2 antigen was shown to exhibit a very specific initial localization pattern after intravenous injection, i.e. in the periellipsoidal lymphocyte sheaths (PELS) and the surrounding ring of macrophages. The functional equivalent of these macrophages in mammals, the marginal zone macrophages, were shown to suppress the humoral responses against TI-2 antigens. Therefore we investigated whether other standard TI-2 antigen models also induce low antibody responses, whether this low response is dose-dependent, and whether macrophages are responsible for this low response. It was found that other TI-2 antigens, such as hydroxyethyl starch and detoxified lipopolysaccharides, also induced very low IgM and IgG responses, indicating a general phenomenon that could not be overcome by using a higher dose of antigen. In addition, selective depletion of splenic macrophages with liposomes containing dichloromethylene diphosphonate prior to immunization increased the specific humoral response to TD and TI-1 antigens, but failed to do so for TI-2 antigen. This result indicates that the low humoral responses are not (only) due to a macrophage suppressive activity but also to other yet unknown mechanisms, for example the lack of responsive B cells in the splenic PELS.

Animals↗
PubMed1998

Antigen detection in vivo after immunization with different presentation forms of rabies virus antigen, II. Cellular, but not humoral, systemic immune responses against rabies virus immune-stimulating complexes are macrophage dependent.

In this paper we describe the effect of depletion of splenic macrophages on the uptake, and immune response against, different formulations of rabies virus antigen. Splenic macrophages were removed by intravenous injection with clodronate liposomes. beta-propiolacton inactivated rabies virus (RV-BPL) and immune-stimulating complexes (iscom) containing these antigens were given to macrophage-depleted and control mice. In the absence of phagocytic cells in the spleen, antigen is still trapped in the red pulp and to a lesser extent in the peri-arteriolar lymphocyte sheaths (PALS) for both antigen formulations. The localization pattern in the main area of immune response induction, namely the follicles, was unaltered after macrophage depletion. Functionally, the depletion of splenic and liver macrophages had no influence on the induction of specific antibody responses in both RV-BPL or RV-iscom immunized mice, even though the latter presentation form was clearly associated with specific localization in the marginal metallophillic macrophages. In RV-BPL immunized mice, macrophage depletion had no influence on proliferative T-cell responses. However, macrophage-depleted mice that were immunized with RV-iscom showed a significant decrease in proliferative T-cell responses. These results confirm existing ideas on the spleen as a physical filter rather than an induction site for humoral responses and shed new light on the efficient role of iscoms as antigen-presenting moieties in relation to their specific in vivo localization patterns and partial macrophage dependency.

Animals↗
PubMed1998

Assessment of side effects induced by injection of different adjuvant/antigen combinations in rabbits and mice.

We evaluated the side effects induced by injection of Freund's adjuvant (FA) and alternative adjuvants combined with different antigens. Rabbits and mice were injected subcutaneously, intramuscularly (rabbits) and intraperitoneally (mice) with different adjuvants (FA, Specol, RIBI, TiterMax, Montanide ISA50) in combination with several types of antigens (synthetic peptides, autoantigen, glycolipid, protein, mycoplasma or viruses). The effects of treatment on the animals' well-being were assessed by clinical and behavioural changes (POT and LABORAS assays) and gross and histopathological changes. In rabbits, treatment did not appear to induce acute or prolonged pain and distress. Mice showed behavioural changes immediately after (predominantly secondary) immunization. Injection of several adjuvant/antigen mixtures resulted in severe pathological changes, depending on adjuvant, type of antigen, animal species used and route of injection. Both rabbits and mice showed pathological changes ranging from marked to severe after injection of FA, and ranging from minimal to marked after Specol and Montanide injections. Pathological changes after RIBI injections were severe in rabbits, though slight in mice. After TiterMax injections, pathological changes were moderate in rabbits, though severe in mice. In conclusion, injection of FA according to present guidelines resulted mostly in severe pathological changes, whereas only very few clinical and behavioural signs indicated prolonged severe pain. Our findings indicate that Montanide ISA50 and Specol induce acceptable antibody titres, and cause fewer pathological changes than FA. Thus they are effective alternatives to FA.

Adjuvants, Immunologic↗
PubMed1998

Orally administered Lactobacillus strains differentially affect the direction and efficacy of the immune response.

In mice, strain dependent cytokine production profiles are induced after oral administration of Lactobacillus. Such a cytokine profile seems to determine the direction and efficacy of the humoral response. In SJL mice lactobacilli are able to enhance or inhibit the development of disease after induction of experimental autoimmune encephalomyelitis (EAE). Immuno-histochemical analysis of cytokine profiles showed that differential modulation is obtained dependent on the Lactobacillus strain applied. Serum antibody responses to i.p. immunisation with chicken gamma globulin in BALB/c mice are also modulated by oral application of Lactobacillus. Lactobacilli are now being developed as safe live antigen carriers for application in vaccine technology, but also for the excretion of autoantigens in order to induce tolerance. The findings of this study imply that by proper strain selection the direction of the response can be influenced by the induction of a specific cytokine profile.

Adjuvants, Immunologic↗
PubMed1997

Heterogeneity of pituitary folliculo-stellate cells: implications for interleukin-6 production and accessory function in vitro.

The population of folliculo-stellate (FS) cells of the rat anterior pituitary has been shown to be ultrastructurally and immunohistochemically heterogeneous. Based on the overlap of ultrastructural characteristics, the localization in the anterior pituitary and the co-expression within the same cel of the S-100 protein (a marker for FS cells) and MHC-class II determinants (an immune marker) we concluded that a partial overlap exists between the population of FS cells and the monocyte-derived dendritic cells (DC). In this report we describe that interleukin-6 (IL-6) immunoreactivity was found in situ in stellate cells of the rat, mouse and human anterior pituitary at a very low density (< 1% of the cells); the topography was reminiscent of the distribution of FS cells. In the present study we also analyse three different pituitary cell separation methods, in order to study the functional heterogeneity of the FS cells in vitro, and to verify whether functionally distinct subpopulations exist within the FS cell group. Production of bioactive IL-6 was measured in conditioned media of rat anterior pituitary cells separated by (i) bovine serum albumin (BSA) gradient sedimentation at 1 g, (ii) Nycodenz gradient and (iii) a magnetic cell separation (MACS) technique. Production of bioactive IL-6 by cell cultures of 1 to 4 days was correlated with the proportional number of S100 immunoreactive and S100 producing cells, but was not correlated with the proportional number of MHC-class II expressing (OX6-positive) dendritic cells (DC). The distribution pattern of OX6-positive DC was found to partly overlap with the distribution pattern of S100-positive cells in the BSA gradient. Co-sedimentation of S100-positive FS cells and MHC-class II-expressing DC was not restricted to the top fractions of the BSA gradient, but was also found in the low density Nycodenz fraction. MACS separation of the rat anterior pituitary cells resulted into a population enriched in OX6 and OX62 positive DC and a population devoid of such cells, while S100+ cells were equally divided into these two subpopulations. Although there was a significantly decreased production of IL-6 as compared to that of an original pituitary cell population, both MACS separated populations were equal in IL-6 production. The diminution in IL-6 production in both populations may be the result of an impediment of paracrine communication due to the MACS separation into these two populations. Our data also show that a subpopulation of FS cells was capable of stimulating T cell proliferation in vitro. Concomitantly with the distribution pattern of S100- and OX6-immunoreactive cells in the BSA and Nycodenz gradient fractions, we found a similar pattern of stimulation of T cell proliferation. Unlike the IL-6 production pattern, the T cell stimulating capacity was present in the MHC-class II-enriched cell population but absent in the MHC-class II-depleted cell population. These findings-together with earlier in situ histochemical data-suggest that there is an OX6+ S100- subpopulation of FS cells in the anterior pituitary that in itself is capable of stimulating T cell proliferation in vitro, and acts as lymphoid DC. There is also an S100+ OX6- population that is unable to stimulate T cell proliferation in vitro. Both populations are able to produce IL-6, but probably need stimuli from other subpopulations of pituitary cells (or exogeneous stimuli) to produce maximal amounts of IL-6.

Animals↗
PubMed1997

Increased adjuvant efficacy in stimulation of antibody responses after macrophage elimination in vivo.

To investigate whether macrophages influence the efficacy of adjuvants, we locally eliminated lymph node macrophages with dichloromethylene diphosphonate containing-liposomes before primary immunization. After macrophage elimination, animals were immunized with a soluble antigen (TNP-KLH; 2,4,6-trinitrophenyl-keyhole limpet haemocyanin) either in phosphate-buffered saline (PBS), in complete Freund's adjuvant (CFA), or in Specol is a water-in-oil emulsion, considered to be less aggressive than CFA, but equally effective. A secondary immunization followed with TNP-KLH. In vivo macrophage elimination before Specol/TNP-KLH immunization resulted in increased adjuvant efficacy as measured by (primary) antibody responses. This suggests that the activity of Specol is not primarily mediated through macrophages but rather through other antigen-presenting cell types (e.g. dendritic cells, B cells, fibroblasts). The overall quality of produced antibodies, in terms of isotype distribution and affinity maturation, remained the same. After primary injection, CFA/TNP-KLH immunization resulted in significantly higher antibody responses in macrophage-depleted animals and antibody responses did not increase significantly after secondary immunization. However, a booster effect was found when macrophages were not eliminated before CFA/TNP-KLH immunization, suggesting that the presence of macrophages during the first weeks of the primary immune response is essential for the induction of an effective secondary response in CFA immunizations. In conclusion, macrophage depletion before immunization with a soluble T-cell-dependent antigen combined with Specol may enhance specific antibody responses without changing the isotype or affinity of the antibodies.

Adjuvants, Immunologic↗