Consumption of fish oils (FO) enriched with the n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), is beneficial to a variety of inflammatory disorders due, in part, to the alteration of membrane composition of T-lymphocytes and other immune cells. We previously observed that down-regulation of proliferation and cytokine synthesis by CD4+ T-cells in mice fed diets rich in n-3 PUFA was dependent on the involvement of CD28, a co-stimulatory molecule necessary for T-cell activation. Since the co-receptor homologues, CD28 and CTLA-4, have opposing effects on T-cell activation, we hypothesized that the balance of costimulatory and downregulatory properties of CD28 and CTLA-4, respectively, would be altered by diet. A significant increase (p<0.05) in CD28 and CTLA-4 surface expression was observed in CD4+ T-cells post-stimulation with phorbol ester and calcium ionophore (PMA/Iono) or anti-CD3 and anti-CD28 (&#945;CD3/CD28) antibodies in all diet groups. A significant increase (p<0.01; 20%) in the number of CD28 molecules was observed in n-3 PUFA vs. CO-fed mice after 48 h of in vitro CD4+ T-cell activation, and both CTLA-4 mRNA transcript and protein levels were upregulated by 50% at 72 h post-activation (p<0.01). Treatment with anti-CTLA-4 mAb in vivo in Mycobacterium bovis (BCG)-vaccinated mice did not alter the suppressive effects of dietary n-3 PUFA on antigen (PPD)-induced lymphocyte proliferation or delayed hypersensitivity reactions. T-cells from both the C57BL/6 and IL-10mice fed dietary n-3 PUFA after 72 h of in vitro stimulation with &#945;CD3/CD28. CD4T-cells from C57BL/6 mice fed DHA produced significantly less IFN&#947; and IL-10, while CD4T-cells from IL-10Ligation of CD28 upregulates IL-10 receptor (IL-10R) expression on CD4+ T-cells. Therefore, we hypothesized that dietary n-3 PUFA would suppress T-cell function through the effects of IL-10. Surprisingly, the proliferation of purified splenic CD4+ T-cells activated in vitro with &#945;CD3/CD28 was suppressed by dietary n-3 PUFA in both conventional mice (C57BL/6) and IL-10 gene knockout (IL-10(-/-)) mice. Furthermore, IL-10R cell surface expression was significantly down-regulated on CD4+ T-cells from both the C67BL/6 and IL-10(-/-) mice fed dietary n-3 PUFA produced significantly more IFN&#947; compared to the CO-fed group.

In addition to their activity against intracellular pathogens, it is now clear that CD8+ T-lymphocytes also mediate anti-tissue responses. In order to manipulate these responses in the setting of tumor immunity or autoimmunity, it is necessary that we understand the parameters that promote CD8+ activation. In the first section of this thesis, a transgenic mouse model was used to explore the effectiveness of peptide/adjuvant-based and dendritic cell (DC)-based vaccination techniques at eliciting CD8-mediated anti-pancreatic responses. It was found that, while peptide vaccines were unable to stimulate autoimmunity, the transfer of DCs promoted autoimmune diabetes in a manner that was dependent upon the toll-like receptor (TLR)-based maturation of the DCs. Furthermore, the diabetes induction was dependent upon the engagement of the immunodominant CD8+ population and a second T-cell specificity, indicating that polyclonal responses may be required for effective tissue destruction. In the second section of this thesis, I explored the requirements for CD28-signaling during the activation of naïve self-reactive CD8+ T-cells. The transfer of mature DCs was insufficient to promote diabetes in CD28-deficient animals, whereas infection with lymphocytic choriomeningitis virus could induce diabetes in the same animals. Anti-tissue responses were further explored in tumor-bearing mice following DC transfer and demonstrated that a critical determinant of the induction of anti-tissue immunity in the absence of CD28-derived costimulatory signals, was the persistence of antigen presentation. In the final section of this thesis, I explored the role of nuclear factor kappa B 1 (NF-κB1) in DC maturation using the DC transfer model described above. Surprisingly, NF-κB1-deficient DCs were capable of inducing diabetes without the need for external stimulation. Furthermore, the absence of NF-κB1 in unstimulated DCs was associated with dysregulated production of tumor necrosis factor alpha (TNF-α), and this cytokine was required for the proper upregulation of the cytotoxic effector molecule granzyme B in CD8+ T-cells that infiltrated the pancreatic islets. This work therefore presents a novel model of autoimmune tissue destruction, in which defined genes and pathways that contribute to DC-T-cell interactions can be explored in an in vivo non-TCR transgenic setting.

Thesis (Ph. D.)--Case Western Reserve University, 2008. / [School of Medicine] Department of Pathology. Includes bibliographical references.

Thesis (Ph. D.)--University of Virginia, 1998. / Includes bibliographical references (p. 120-172). Also available online through Digital Dissertations.

Thesis (Ph. D.)--Cornell University, August, 2007. / Vita. Includes bibliographical references (leaves 145-165).

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

This series of studies began with an examination of the effects of training status (Tr vs UTr) and sex on the resting levels and redistribution of senescent (CD28-CD57+) and naïve (CD28+CD57-) T-lymphocytes (CD4+, CD8+) following a treadmill test to volitional exhaustion. In this first study exercise elicited a redistribution of senescent CD4+, CD8+ and naïve CD4+,CD8+ T-lymphocytes. UTr had a higher proportion of senescent and a lower proportion of naïve CD8+ T-lymphocytes than Tr. Males had a higher proportion of senescent and lower proportion of naïve T-lymphocytes than females with the highest percentage of senescent and lowest percentage of naïve T-lymphocytes observed in UTr males. CMV was a covariate in the senescent and naïve CD8+ T-lymphocytes. This study highlighted important sex and training status differences in the senescent and naïve T-lymphocyte redistribution in response to exercise. These findings led on to an investigation of the T-lymphocyte (CD4+, CD8+, γδ+) response to a period of 2 weeks increased volume training (39% increase in volume) in trained females (Tr, n=13) compared to a period of 2 weeks habitual activity in female controls (UTr, n=13). This second study observed no difference in the resting T-lymphocyte profile from the pre to post increased volume training period. The resting number of CD3+ and proportion of γδ+ T-lymphocytes was greater in the Tr compared to the UTr. The resting proportion of CD4+T-lymphocytes and the CD4+:CD8+ ratio was greater in the UTr compared to the Tr. CMV was a covariate in the analysis of CD8+, CD28+ CD8+, and naïve CD8+ T-lymphocyte cell numbers but not in the analysis of T-lymphocyte proportions. The increased volume training period had no effect on resting T-lymphocyte populations in Tr females, and T-lymphocyte populations also did not change with 2 weeks of habitual exercise in UTr. The total energy, carbohydrate and protein intake was greater in Tr compared to the UTr during the increased volume training period and was greater than normal in the Tr group. These dietary influences may partly explain the absence of any change in T-lymphocyte proportions pre to post training period in Tr. Differences in the proportions of γδ+, CD4+ and the ratio of CD4+:CD8+ T-lymphocytes at rest between the Tr and UTr warrants further investigation. The final study of this series is presented in two parts. The first part focused on the influence of 4 weeks supplementation at 0.1g/kg body mass/day with n-3 polyunsaturated fatty acids (PUFA) as fish oil (FO, n=10), or short-chain saturated fatty acids (SFA) as coconut oil (CO, n=10) on T-lymphocyte (CD4+,CD8+, γδ+) differentiated populations at rest and in response to exercise in trained males. Changes were examined by Day (Baseline to pre supplementation, Pre Sup (4 week control period), and pre supplementation to post supplementation, Post Sup (4 week supplementation period)). During a 4 week baseline control period no changes were observed in the blood lipid profile in both FO and CO groups. During the control period a main effect of exercise was observed in all the CD3+ and γδ+ T-lymphocytes subsets. During the control period an interaction of group-by-day was observed in the senescent CD8+ T-lymphocytes from BL to Pre Sup the proportion and number decreased in the FO group and increased in the CO group. Inclusion of CMV as a covariate introduced a main effect of group on the CD4+ naïve proportions and cell counts and the group-by-day interaction observed on the CD8+ senescent T-lymphocyte proportions and cell counts disappeared. During the 4 week supplementation period this study observed an increase in the n-3 PUFAs, EPA (20:5n-3), DHA (22:6n-3) and DPA (22:5n-3) in the FO group but not in the CO group (with no changes in blood lipid profile on CO). During the supplementation period a main effect of exercise was observed in all the CD3+ and γδ+ T-lymphocyte subsets except for the proportion of CD8+ naïve T-lymphocytes. The proportion of CD8+ naïve T-lymphocytes was lower at rest and in response to exercise in FO and CO groups after supplementation. CMV was a significant covariate in senescent CD4+ T-lymphocyte cell counts. At the post exercise time point the γδ+ T-lymphocyte count increased in the FO group but decreased in the CO group, following the supplementation period. However, this observation did not quite reach statistical significance. Although a difference between the groups was evident for γδ+ T-lymphocyte count and proportion there was insufficient evidence to conclude whether the difference was supplement related. It would appear that dose, duration and type of fatty acids ingested could all be important in the overall response but these require further study. The second part of this final study investigated the influence of 4 week supplementation at 0.1g/kg body mass/day with n-3 polyunsaturated fatty acids (PUFA) as fish oil (FO, n=10) or short-chain saturated fatty acids (SFA) as coconut oil (CO, n=10) on plasma Th1 cytokine: IL-2, TNF- α and IFN-γ, and Th2 cytokine IL-4, IL-6 and IL-10 concentrations, and expression of the T-lymphocyte activation marker CD69 at rest and in response to exercise in trained males. Changes were examined by Day (Baseline to pre supplementation (4 week control period), and pre supplementation to post supplementation (4 week supplementation period)). This study observed an increase in n-3 PUFAs, EPA (20:5n-3), DHA (22:6n-3) and DPA (22:5n-3) in the FO group but not in the CO group. There was a significant mobilisation of activated CD4+ CD69+ and CD8+ CD69+ (P<0.05) T-lymphocyte numbers in response to exercise in both FO and CO groups. CMV infection was a significant covariate on the number and proportion of CD4+CD69+ T-lymphocytes (P<0.05) but not on the number or proportion of CD8+CD69+ T-lymphocytes. During the supplementation period there was a significant effect of Day on TNF-α, IL-6, IL-4 and IL-2 with IFN-γ and IL-10 trending towards a difference. The plasma cytokine concentration was greater at post supplementation compared to pre supplementation for both FO and CO groups. Latent CMV infection was a significant covariate for TNF-α, IL-6, IL-4, IL-2, IFN-γ and IL-10. In the current study we observed no evidence of a difference between the CO and FO groups for early T-lymphocyte activation marker or plasma cytokine concentrations despite the membrane lipid composition change over the 4 week supplementation period. It would appear that the plasma Th1 and Th2 cytokine concentration increased from pre supplementation to post supplementation on both PUFA and SFA, highlighting a potential link between fatty acid incorporation and cytokine expression that needs closer examination. The results of this series of studies highlight that sex and training status impact upon the T-lymphocyte pool at rest and in response to exercise. Increasing the volume of training for 2 weeks without dietary restriction does not alter the resting T-lymphocyte pool in trained females. Alterations to the T-lymphocyte pool at rest and in response to exercise are not related to FO or CO supplementation. Furthermore, the response of Th1, Th2 plasma cytokines, and the early activation marker CD69 at rest and in response to exercise does not differ between a group supplemented with FO compared to a group supplemented with CO it would appear that Th1 and Th2 plasma cytokines increase post supplementation in both groups. Particular avenues of interest for future research would be, to explore the sex differences in T-lymphocyte subsets at rest and in response to exercise, to determine whether these sex differences are key in susceptibility to disease/infection and to determine the tissue targets of lymphocytes mobilised during exercise.

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / "July 1998." Typescript. Vita. Includes bibliographical references (leaves 190-217). Also available on the Internet.