Polymorphonuclear leukocytes infiltrate tissues in response to an inflammatory stimulus such as endotoxin or parasite products. Previous studies have shown an extensive cellular infilteration about the parasitized skeletal muscle of mouse infected with the nematode, Trichinella spiralis. Infection of the host with Trichinella pseudospiralis, on the other hand, is associated with a dramatic suppression of inflammatory cellular response. Prostaglandin Bi is a product of arachidonic acid metabolism and is synthesized by variety of cell types. Prostaglandins of the E series have been generally known to suppress inflammatory responses. In the present study, I have investigated the possible relation between plasma prostaglandin Bi levels and host cellular response in infected mice. Concentrations of prostaglandin Bi in mice plasma were measured at 5, 11, and 21 days after infection with larvae of either nematode species by enzyme immunoassay. There were noticeable elevations in the concentrations of prostaglanding Bi in samples of mice infected with Trichinella pseudospiralis compared to controls. Conversely, decreased levels of prostaglandin Bi were observed in samples from the mice infected with Trichinella spiralis. These results suggest that the differences observed in the host inflammatory response to infection with Trichinella spiralis versus Trichinella pseudospiralis might be associated with recognized properties of prostaglandin Bi· In this connection, I have suggested three possible mechanisms by which the differences of inflammatory response in relation to PGEi production may be explained.

The papers included in this thesis examine the host–parasite relationship in small and large animals following experimental challenges with Neospora caninum. This apicomplexan parasite is a major cause of abortion and reproductive losses in cattle worldwide. Economic and welfare issues make the development of a vaccine against the transplacental transmission of Neospora highly desirable. This thesis evaluates the host-parasite interactions in a non-pregnant mouse model examining whether the actively multiplying stage of the parasite (tachyzoite) could be attenuated through prolonged in vitro cultivation (passage) and used as a live vaccine. We show that continued maintenance of tachyzoites in tissue culture produced significantly reduced levels of morbidity and mortality in the mice following challenge, compared to mice receiving virulent parasites. Inoculation with a sub-lethal dose of tachyzoites was shown to protect against a subsequent lethal challenge of virulent parasites. Mice showing higher levels of cell mediated immunity (CMI) (antigen-specific splenocyte proliferation and interferon-γ (IFN-γ) production) had lower parasite burdens compared to mice with less pronounced CMI responses. Combined, these works show that it is possible to protect against a lethal challenge using attenuated tachyzoites and that a strong T-helper Type-1 CMI response is involved in protection and in reducing clinical disease severity. As the most commonly known route of infection with N. caninum is transplacental, from dam to foetus, we also wanted to examine the host-parasite relationship in pregnant cattle. This was done through the serial examination of the maternal and foetal immune responses of experimentally challenged cattle under controlled conditions at different stages throughout pregnancy. These works show the importance of the timing, location and magnitude of multiple components of the host immune response in determining foetal survival and also whether vertical transmission occurs. We show that both the maternal and foetal immune responses are critical in determining the clinical outcome of infection. A strong maternal CMI response was shown to aid foetal survival by reducing the numbers of parasites reaching and thus damaging the placenta. Due to the syndesmychorial nature of the ruminant placenta, any foetal responses observed are as a result of foetal infection. These experiments show that as pregnancy progresses the foetus goes from being immunologically immature and incapable of mounting a protective immune response (70 days of gestation (dg)) to becoming capable of mounting parasite-specific humoral, innate and CMI responses from around 140dg onwards. The experiments in pregnant cattle confirm the importance of parasite-specific proliferation and IFN-γ production, in reducing the magnitude of the parasite challenge reaching the maternal–foetal interface and aiding foetal survival. We also examined the immunodominant parasite peptides expressed in HPLC fractionated tachyzoite antigen, which are recognised by the cellular immune response of experimentally challenged cattle. Through LC-ESI-MS/MS, 6 Neospora proteins (including SAG1, SRS2 and GRA2) and a number of Toxoplasma gondii orthologues were identified and found to be recognised by CD4+ T-cells. These works collectively demonstrate the complexity of the host-parasite interaction in Neospora infections and show the importance of a CMI response in protection against the parasite.

Graduation date: 1995

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / abstract / Microbiology / Master / Master of Philosophy

Proper immune function is indispensable, as failure to mount an immune response against a pathogen can lead to serious complications or even death. T cells act by enhancing the activation of phagocytic cells as well as the activation of B cells. Their widespread influence on an immune response makes optimal T cell activation vital. Maximal T cell proliferation and survival is accomplished by stimulation with antigen, a costimulatory signal, and an adjuvant. However, excessive T cell activation can lead to chronic B cell activation and the production of autoantibodies, a hallmark of autoimmune disease. In this thesis, optimal T cell stimulation was studied using an in vivo adoptive transfer model. Results showed that antigen stimulation of T cells along with ligation of the costimulatory molecule OX40 led to an accumulation of antigen-specific cells. OX40 ligation allowed the antigen specific cells to proceed through more cell cycles than cells stimulated with antigen alone. The addition of the adjuvant lipopolysaceharide (LPS) to this system allowed for increased cell survival. However, the continual presence of an adjuvant may also have injurious effects. This was highlighted with the appearance of "Toxic Oil Syndrome" (TOS) in which an adulterated rapeseed oil, an oil with known adjuvant activity, was sold for human consumption. People developed an autoimmune condition characterized by polyclonal B cell activation and autoantibody production. A genetic predisposition was implicated with TOS and was further investigated in this thesis. Although the A. SW mouse has the genetically susceptible genotype, these mice did not develop TOS following exposure to "toxic oil" indicating that other factors may be important in TOS susceptibility. Extending the techniques used in these studies and applying them to the canine immune system was the final topic investigated in this series of studies. Understanding immune pathways of the mammalian immune system is particularly important for comparative studies when dogs are used as models to investigate human immune system disorders. These studies combined will allow for a better understanding of the balance between an optimal immune response and an imbalance leading to hypersensitivity or immunosuppression, as well as interspecies relationships. / Graduation date: 2002

It was hypothesized that alterations in plasma concentrations of corticosterone (CS) and prolactin (PRL) may be at least partially responsible for polychlorinated biphenyl (PCB)-induced immunosuppression. A 2 by 2 factorial experiment examined the interactions of PCB and P815, an allogeneic tumor, on plasma concentrations of CS and PRL, and on body, spleen, and thymus weights. The PCB dosage used (10 mg/kg) was previously shown to suppress immune response to the tumor. The four study groups were: Group A (vehicle control), Group B (tumor only), Group C (PCB only), and Group D (tumor plus PCB). Mice received one dose of PCB (Groups C and D) or carrier (Groups A and B) on day -1; tumor (Groups B and D) or carrier (Groups A and C) was injected intraperitoneally on day 0. In Experiment 1, animals were killed on days -1, -0.6, 0 through 10, 21, 42, and 84. Body, spleen, and thymus weights were measured. Plasma samples were obtained for CS and PRL measurements. In Experiment 2, the study was repeated with samples obtained only on days 3 and 10. Group A body weights increased steadily throughout Experiment 1. Relative to Group A, the weight gain in Group B was significantly (p < 0.05) higher. Group C lost weight on days 0 through 6, and gained significantly (p < 0.05) less weight than Group A. Group D gained significantly (p < 0.05) less weight than Groups A, B, and C. As a percent of body weight, spleen weight remained constant over 21 days in Experiment 1 in both Groups A and D. Compared to Group A, Group B showed significantly (p < 0.05) increased spleen percent body weight while Group C showed significantly (p < 0.05) decreased spleen percent body weight. As a percent of body weight, thymus weight remained constant for 21 days in Experiment 1 in Group A. Groups Band C were similar (p > 0.05) and showed a decreased thymus percent body weight compared to Group A. Group D showed significantly (p < 0.05) decreased thymus percent body weight relative to the other three groups. Mean CS concentrations in Experiment 1 in Groups A and B were similar (p < 0.05). Relative to Groups A and B, Group C CS concentrations were elevated, with a peak of 126.1 ng/ml on day 4. Group D CS concentrations were higher than the other three groups, peaking at 294.1 ng/ml on day 10. There was no significant difference in PRL concentrations in Groups A, B, and C in Experiment 1 (p > 0.05). Mean PRL concentration in Group D was significantly (p < 0.05) lower than in the other three groups. The results of Experiment 2 validated those of Experiment 1. Although absolute values differed, the pattern of changes seen in body and organ weights and in CS and PRL concentrations was similar. An acute exposure to PCB and tumor resulted in an increase in circulating CS concentration and a decrease in circulating PRL concentrations. These changes may contribute to PCB-induced immunosuppressioin. / Graduation date:1992

Probiotics are a live microbial supplement that reside within the intestinal tract and are considered normal flora. The Balb/c mouse model was used to determine if the elimination of probiotics, general LAB species, by antibiotics plays a role in the breakdown of oral tolerance leading to the generation of an immune response to oral antigens. A mouse model was developed for in vivo research regarding probiotic populations and the effect on the induction of oral tolerance. The Balb/c mouse was used to determine if the mouse model had a colonized intestinal tract with probiotics followed by a reduction of probiotics that was done with orally administered antibiotics. After the reduction of probiotics, mice were fed oral antigen, ovalbumin, to determine that an immune response was not shown with oral antigen alone. After the mouse model was set up, mice were then fed oral antigen and then stimulated with immunizations to study the induction of oral tolerance and the possible effect of the absence of probiotics. The results indicated that mice with reduced probiotics and fed with oral antigen alone do not show an immune response. In contrast, mice fed with oral antigen followed by immunization indicate a higher OVA-specific serum IgG. This is evidence that correlates with clinical findings in disease states such as Crohn's Disease and Irritable Bowel Syndrome (IBD). / Department of Biology

Both Immune cells and pathogenic microorganisms require iron for proliferation and multiplication. However, role of iron supplementation on immune function is still unclear. Studies show that iron-deficient mice are protected from developing Experimental Autoimmune Encephalomyelitis (EAE), an animal model of Multiple Sclerosis (MS) in humans. In this project, we developed a mice model of iron overload in (B6.Cg-Tg (Thy1-YFPH) 2Jrs/J mice). Seven mice were injected (ip), 100 μl iron dextran and seven with Phosphate buffered saline (PBS), five days/week for four weeks. Blood samples verified iron overload 170 versus 138μg/dl (P < 0.005). Flow Cytometry revealed high T-cells and low and CD8+ T-cell. Histological sections indicated perivascular immune cell infiltrations in the brain, but not in the spinal cord. Confocal microscopy of spinal cord sections showed myelinated axons with no breaks. The absence of demyelination and clinical signs, but high CD3+ with low CD4+ T-cells suggests an altered immune cell function in iron overload mice that needs further exploration. / Access to thesis permanently restricted to Ball State community only / Department of Physiology and Health Science

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 45-55). / i, 92 leaves, bound ill. 29 cm