Natural killer (NK) cells are a critical component of the immune response against viral infections. NK cell depletion prior to murine cytomegalovirus (MCMV) infections results in increased susceptibility to infection in several mouse strains. The mechanism of protection in C57Bl/6 mice is dependent on the activation of NK cells by Ly49H recognition of m157. Our previous studies have examined important residues of m157 for Ly49H recognition, as well as the contribution of m157 glycosylation to NK cell activation. However, what role the glycophosphatidyl inositol (GPI) anchor of m157 plays in Ly49H activation was unknown. Here we demonstrate that the GPI anchor of m157 regulates the surface expression of the protein. While the GPI anchor was not required for recognition of m157 by the activating or inhibitory Ly49 receptors, expression of GPI-anchored m157 resulted in greater receptor downregulation on NK cells, as well as increased NK cell cytotoxicity compared to transmembrane m157. In addition to MCMV infections, NK cells have been shown to participate in the immune response to influenza A virus (IAV). However the exact role of NK cells in IAV infection is less clear, as some studies have found NK cells to be protective, while others have shown that NK cells cause lethal immunopathology. It is likely that the severity of IAV infection may dictate the NK cell response to IAV infection (i.e. protective vs. immunopathogenic). Herein we show that NK cell accumulation in IAV-infected lungs and lung-draining lymph nodes (DLN) is regulated by the severity of IAV infection, where there is increased NK cell accumulation in the lungs during high dose IAV infection, and greater NK cell accumulation in the DLN in low dose IAV infections. Despite significant NK cell recruitment to the lung during IAV infection, as well as previously published studies demonstrating the importance of NK cells to IAV immunity, NK cell depletion prior to IAV infection did not result in a significant change in morbidity or mortality. Interestingly, NK cell depletion resulted in a significantly greater number of CD4 T cells in the IAV infected lung. Further, both CD4 and CD8 T cells in NK-depleted mice showed increased IFN-Γ production. Finally, while not statistically significant, NK cell depletion resulted in a trend toward greater protection from heterosubtypic IAV challenge infections. Taken together these results suggest that NK cells may either regulate the adaptive immune response to IAV infection through suppression of CD4 and CD8 T cells, or that the T cell response to IAV infection is able to compensate for the loss of NK cells. Moreover, while NK cell suppression of T cell function during a primary IAV infection does not result in increased susceptibility to primary IAV infections, NK cell regulation of adaptive immune responses may suppress the memory T cell response, and therefore leave the host more susceptible to secondary infections. Overall the studies presented herein demonstrate a complex role for NK cells in the immune response against viral infections. Ly49H+ NK cells directly kill MCMV-infected cells and m157-bearing targets, but NK cell activation is regulated by ligand density, as well as the ligand membrane anchor. Additionally, NK cells suppress adaptive immune responses during a primary IAV infection, resulting in changes to the T cell response during both primary and memory responses.

Antigen-specific CD8 T cells play a critical role in protecting the host from infection by intracellular pathogens including viruses, bacteria and parasites. During the course of an infection, antigen-specific CD8 T cells undergo proliferative expansion to increase in number, which is followed by contraction and generation of a stable pool of long-lived memory cells. Importantly, memory CD8 T cells provide enhanced resistance to re-infection by the same pathogen. Moreover, the number of memory CD8 T cells correlates strongly with the level of protection against re-infection. Therefore, vaccines designed to promote cellular immunity should logically focus on achieving sufficiently high number of these memory cells for protection. Most current vaccines have relied on inducing antibodies to protect the host by neutralizing pathogens or blocking pathogen entry into the cells. However, there is a recognized need to design vaccines that also stimulate a strong CD8 T cell component of the adaptive immune response in addition to antibodies. Importantly, inflammatory cytokines induced by infection or vaccination with adjuvant act directly or indirectly on CD8 T cells to modulate their expansion, contraction and acquisition of memory characteristics. Thus, an understanding of how inflammatory cytokines regulate CD8 T cell memory differentiation may help guide the strategies for rational vaccine design. My studies examine the roles of inflammatory cytokines in regulating CD8 T cell memory differentiation. Specifically, my studies investigate the timing of inflammatory cytokine exposure and the role of type I IFNs and IL-12 in regulating effector/memory CD8 T cell differentiation, and exploiting the cross-presentation pathway to rapidly generate protective CD8 T cell immunity. Specifically, my results indicate that (i) encounter with inflammatory cytokines during the rapid proliferative phase deflects CD8 T cell differentiation away from memory towards a sustained effector program, (ii) that direct signaling by either type I IFN or IL-12 to the responding CD8 T cells promotes maximal expansion, but neither of these cytokines is essential to regulate the effector/memory differentiation program, and (iii) cross-priming with both cell-associated antigen and antigen-coated, biodegradable microspheres, accelerates CD8 T cell memory development that can be exploited to rapidly generate protective CD8 T cell immunity.

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis-induced hospitalization in young children. A natural RSV infection fails to elicit long-lasting immunity, further increasing the need for an effective vaccine. Despite the significant healthcare burden, there is no licensed RSV vaccine currently available. While most RSV vaccine strategies focus on the induction of humoral immunity, high antibody titers do not prevent RSV infection. It remains unclear if protective immunity can be achieved through robust cellular immunity. Previous work has indicated that a relatively low frequency of virus-specific CD8 T cells is induced following an RSV infection in human infants. In addition, RSV-specific memory CD8 T cells diminish to almost undetectable frequencies in the blood of the elderly. The lack of long-lasting immunity against RSV may be explained by an absence or low frequency of memory CD8 T cells within the lung following infection. However, I determined that the majority of effector CD8 T cells reside within the lung tissue following infection with either RSV or influenza A virus (IAV), both of which replicate primarily in the airways. In addition, approximately 70% of antigen-experienced memory CD8 T cells persist in the lung tissue at day 30 following RSV infection. In contrast, the majority of CD8 T cells remain in the pulmonary vasculature following intranasal infection with either of the systemically replicating viruses lymphocytic choriomeningitis virus or vaccinia virus. Therefore, the tissue tropism of a virus will determine if CD8 T cells preferentially accumulate in the lung tissue following infection of the respiratory tract. An experimental formalin-inactivated RSV (FI-RSV) vaccine caused enhanced respiratory disease in vaccinated children following a natural RSV infection. Incomplete knowledge of the underlying immunological mechanisms that were responsible for mediating the enhanced disease has greatly hampered vaccine development. Previous studies have indicated that eosinophils, non-neutralizing antibodies, and CD4 T cells may be required to elicit FI-RSV vaccine-enhanced disease. I determined that distinct CD4 T cell subsets mediate individual disease parameters. The Th2-biased immune response, but not eosinophils specifically, was responsible for induction of airway hyperresponsiveness and mucus hypersecretion. On the other hand, the Th1-associated pro-inflammatory cytokine TNF-α was required to mediate baseline pulmonary dysfunction and weight loss. Lastly, while depletion of CD4 T cells ameliorated all disease parameters evaluated, the antibody titers remained unaltered in depleted mice. Thus, antibodies induced by FI-RSV immunization were not required for vaccine-enhanced disease. My data demonstrate that discrete disease manifestations associated with FI-RSV immunization are orchestrated by distinct subsets of CD4 T cells. The CD8 T cell response is believed to contribute to both pathogen clearance and immunopathology following an acute RSV infection. However, it is unclear if robust memory CD8 T cell responses will protect against an RSV infection. I determined that induction of a high-magnitude, epitope-specific memory CD8 T cell pool mediated increased viral clearance following RSV challenge. However, mice with robust secondary CD8 T cell responses exhibit increased airway dysfunction, weight loss, and mortality as compared to mock-immunized mice undergoing an acute RSV infection. The enhanced disease severity was unique to the context of an RSV infection as similarly immunized mice were protected from chge with a lethal dose of a recombinant IAV engineered to express an RSV-derived epitope. In addition, the increased morbidity and mortality was associated with an elevated amount of both IFN-γ and TNF-α in the serum of immunized mice. Neutralization of either IFN-γ or TNF-α led to a significant reduction in disease severity and survival of all mice. These results demonstrate that robust memory CD8 T cell responses enhance viral clearance, but also lead to severe pulmonary immunopathology following RSV infection. Overall, I establish that the majority of effector CD8 T cells are localized within the lung tissue following a respiratory infection, and determine that either memory CD4 or CD8 T cell responses elicits severe immunopathology following a RSV infection.

T-cell acute lymphocytic leukemia (T-ALL) affects approximately 1,500 people per year in the United States, many of them children. The overall survival rate of children with T-ALL is greater than 80%. However, patients in a newly identified subtype called early T-cell progenitor acute lymphocytic leukemia (ETP-ALL), have a survival rate of only 19%. We have used the Sleeping Beauty (SB) transposon/transposase system in mice to model the T-ALL subtypes and identify cancer-causing mutations in the diseases. We have also developed three strains of NOTCH1 transgenic mice. NOTCH1 is a gene that is mutated in over 60% of cases of T-ALL, and these NOTCH1 transgenic mice could be used to better understand the role NOTCH1 plays in T-cell transformation. In order to model T-ALL subtypes we crossed SB mice to Vav-iCre mice, Lck-Cre mice, and CD4-Cre mice. This causes activation of SB in hematopoietic stem cells (HSCs), double negative (DN) thymocytes, and double positive (DP) T-cells, respectively. The Vav/SB tumors were characterized by mutations in Notch1, Ikzf1, and Rasgrp1. The predominant mutations found in the Lck/SB and CD4/SB models were Stat5b, Myc, Gfi1, Whsc1, and Jak1. Microarray was performed on a subset of samples. It was found that the CD4/SB tumors had expression profiles very similar to human ETP-ALL samples, and the Vav/SB tumors had expression profiles very similar to typical T-ALL samples. This data indicates that the cell-of-origin for ETP-ALL may not be an early T-cell progenitor, but instead may be a double positive or single positive T-cell. It also indicates that the cell-of-origin for typical T-ALL may be a stem/progenitor cell of the T-lineage. In order to better study the oncogenic potential of mutant NOTCH1 in T- ALL, we produced three NOTCH1 transgenic mouse strains that mimic the most common NOTCH1 mutations found in human T-ALL patients. These mutations are found in two distinct regions of the gene, the heterodimerization (HD) domain and the PEST domain and can occur alone or in combination. The strains also contain a lox-stop-lox (LSL) cassette in the first exon of NOTCH1, making expression Cre-dependent. Preliminary results from NOTCH1-HD-PEST (NHDP) transgenic mice indicate that, when crossed to Lck-Cre mice, offspring do not develop T- cell lymphoma. However, when NHDP/Lck-Cre mice are crossed to SB mice, the mutant NOTCH1 transgene accelerates a SB-induced model of T-cell lymphoma.

The severe disease associated with seasonal epidemics of influenza A virus (IAV), as well as pandemic outbreaks, have highlighted the necessity for novel, broadly cross-reactive vaccination and therapeutic strategies against IAV. Our studies have focused on the contribution of IAV-specific CD8 T cells to mediating protection following IAV vaccination and infection as IAV-specific CD8 T cells are required for clearance of IAV. Further, IAV-specific CD8 T cells are typically cross-protective as they are generally directed at highly conserved areas of IAV. Recently, influenza virus-like particles (VLPs) have been developed from recombinant baculoviruses containing influenza proteins hemagglutinin (HA) and/or neuraminidase (NA) on the surface and matrix (M1) in the VLP core. Influenza VLPs induce potent antibody responses and have been shown to provide protection from morbidity and mortality during lethal homo- and hetero-subtypic IAV challenge. This suggests that conserved, VLP-induced CD8 T cell responses may also contribute to the overall protective ability of VLPs. However, whether influenza VLPs can induce influenza-specific CD8 T cell responses and if these T cells are protective during IAV challenge remains unknown. Here, I demonstrate that a single, intranasal vaccination with VLPs containing HA and M1 leads to a significant increase in HA533-specific CD8 T cells in the lungs and lung-draining lymph nodes. Our results also indicate that HA533-specific CD8 T cells primed by influenza VLP vaccination are significantly increased in the lungs following lethal IAV challenge. These VLP-induced memory CD8 T cells are critical in providing protection from lethality following subsequent challenge infections, as depletion of CD8 T cells leads to increased mortality, even when total, but not VLP-induced memory, CD8 T cell numbers have been allowed to recover prior to lethal dose IAV challenge. In addition, my studies also importantly demonstrate that these VLP-induced, HA533-specific CD8 T cells aid in protection from high-dose, heterosubtypic IAV infections where CD8 T cell epitopes are conserved, but the targets of neutralizing antibodies have been destroyed. This dissertation further elucidates the requirements for the regulation of the IAV-specific CD8 T cell response in the periphery (i.e. lung) by pDC and CD8α+ DC. Our studies have previously demonstrated that pDC or CD8α+ DC must present viral antigen in the context of MHC class I along with trans-presentation of IL-15 to effector, IAV-specific CD8 T cells in the lungs to protect the T cells from apoptosis and allow generation of the full magnitude CD8 T cell response needed to clear IAV infection. Herein, I demonstrate that in addition to antigen presentation and IL-15, costimulatory molecules on the surface of pDC and CD8α+ DC are also required. However, the specific costimulatory molecules required depends upon both the mouse strain utilized for IAV infection as well as DC subset. In addition to costimulatory molecules, I also demonstrate that the requirement for pDC and CD8α+ DC to be infected differs in order for them to participate in this pulmonary rescue of the IAV-specific CD8 T cell response. While CD8α+ DC are able to efficiently cross-present exogenous antigen, pDC must be directly infected and utilize the endogenous, direct antigen presentation pathway to present viral antigen to IAV-specific CD8 T cells in the lungs during IAV infection. These data suggest there are distinct differences between pDC and CD8α+ DC in their mechanism of regulating the pulmonary IAV-specific CD8 T cell response, which had not been previously appreciated. Together, the results presented herein further detail the mechanism of regulation of effector IAV-specific CD8 T cells by DC as well as the contribution of IAV-specific CD8 T cells to a novel, IAV VLP vaccination strategy. These findings highlight the importance of IAV-specific CD8 T cells in mediating protection following IAV vaccination and infection.

Tim-1 (T cell immunoglobulin mucin domain 1) is a transmembrane protein expressed by many cell types, including activated T cells and B cells. Antibodies to Tim-1 have been shown to decrease severity of airway hyperreactivity and Th2 cytokine production in mice. Current literature suggests Tim-1 functions as a co-stimulatory molecule. We hypothesize that Tim-1 signals in lymphocytes, and that Tim-1 signaling modulates allergic airway disease. Chapter one provides a brief overview of current literature exploring identification of the Tim family of receptors, genetic associations between TIM-1 polymorphisms and human diseases, Tim-1 expression, Tim-1 ligands, studies of antibodies to Tim-1 in various mouse models of human disease, and signaling events downstream of Tim-1 engagement. Chapter two provides detailed experimental methodology. Chapter three details the characterization of Tim-1 deficient mice. Tim-1 deficient mice do not exhibit defects in lymphocyte or myeloid cell development, as determined by numbers of cells present in bone marrow, thymus, spleen, and lymph nodes. C57BL/6 Tim-1 deficient female mice appear to develop an increased number of lymph node cells and also develop anti-double stranded DNA antibodies. Chapter four explores the impact of Tim-1 deficiency in a murine allergic airway disease model, which demonstrated that Tim-1 deficient mice developed increased lung inflammation and increased antigen-specific Th2 cytokine production that was evident in mice backcrossed to both BALB/c and C57BL/6 backgrounds. These phenotypes were not evident using purified naïve CD4+ T cells polarized in vitro. As Tim-1 expression is not restricted to CD4+ T cells, adoptive transfer experiments were performed to determine whether the phenotype observed was due to the deficiency of Tim-1 on CD4+ T cells, non-CD4+ T cells, or Tim-1 deficiency on both CD4+ T cells and non-CD4+ T cells. Chapter five explores the impact of Tim-1 deficiency in a chronic Leishmania major intradermal infection model. Tim-1 deficient mice crossed to both BALB/c and C57BL/6 backrounds demonstrated similar parasite burden over the course of time, but in vitro restimulation of lymph node cells revealed a striking increase in cytokine production that extended to Th1, Th2, and Th17 lineages. Tim-1 signaling in murine B cell lines is explored in Chapter six. A Tim-1 monoclonal antibody conjugated to beads induces phosphorylation of Tim-1 and recruitment of the Src family kinase Fyn. This phosphorylation of Tim-1 is reduced in Fyn-deficient B cell lines. Chapter seven discusses the significance of these findings, relates current literature to these results, and provides some avenues for further exploration of Tim-1 function and signaling.

One major therapeutic target for preventing and treating Alzheimer's Disease (AD) is removal of excess β-amyloid (Aβ) from the brain. Both active and passive immunotherapies targeting Aβ have proven effective in reducing brain Aβ levels and improving cognitive function in mouse transgenic models of AD. However, these approaches can induce adverse neuropathologic effects and immunologic over-activation. Indeed, clinical trials of active Aβ immunotherapy in AD patients were halted due to development of meningoencephalitis, apparently resulting from wide-spread neuroinflammation. Here we show that a more restricted and specific immune re-activation through a single adoptive transfer of Aβ-specific T cells can provide long-term benefits to APPsw+PS1 transgenic mice that last at least 1 1/2 months. Aβ-sensitive splenocytes and lymphocytes were generated in normal mice, re-stimulated with Aβ in vitro, and then adoptively transferred into cognitively-impaired APPsw+PS1 mice. Compared to control transgenic mice through 1 1/2 month post-infusion, those mice that received Aβ-sensitive T cells exhibited a reversal of pre-infusion working memory impairment and demonstrated superior basic mnemonic processing. Step-wise forward Discriminant Function Analysis of behavioral results clearly demonstrated that T cell infused mice performed comparably to wild-type non-transgenics, further emphasizing the extent of cognitive benefit this therapeutic technique afforded. Importantly, a global inflammatory response did not accompany these benefits. Though no overall reductions in Aβ deposition were noted for T cell recipient mice, a subset of T cell infused mice that benefited most in cognitive function had reduced hippocampal burdens, suggesting that hippocampal Aβ burdes did play a role in determining performance capabilities of these mice. Since chronically high levels of beta-amy loid such as those found in APPsw+PS1 mice cause immune hypo-responsive/tolerance to Aβ, our results indicate that adoptive transfer of Aβ-sensitive T-cells can supercede such immune tolerance to Aβ, and may provide a safe, long-lasting therapy for AD.

Airway hyperresponsiveness (AHR) is one of the primary features of allergic airways disease. Despite continuous allergen exposure atopic asthmatics do not develop progressively worsening AHR. The mechanism(s) that limit AHR are unknown. Two valid candidates are regulatory T cells (Treg) and antigen presenting cells (APC). Dendritic cells (DC) are the main APC within the airways. Presentation of allergens to T cells can result in the differentiation and expansion of different subsets of T cells including effector Treg cells. The precise role of Treg and DC in the attenuation of allergen-induced AHR remains unknown. The general aim of this thesis is to investigate mechanisms to limit AHR in a murine model of atopic asthma. Specific aims are to: 1. develop a murine model of allergen-induced attenuation of AHR, 2. determine the potential role of regulatory T cells (Treg) in allergen-induced AHR attenuation, and 3. determine the potential role of airway dendritic cells (DC) in allergen-induced AHR attenuation. Balb/c mice were sensitised with intraperitoneal Ovalbumin (OVA) in aluminium hydroxide and challenged with a single, 3-weeks or 6-weeks of OVA aerosols. Aerosols were 1% OVA in sterile saline delivered for 30 minutes for three days per week. Animals were sacrificed 24 hours after the final aerosol for measurements of lung function and Methacholine (MCh) responsiveness (low-frequency forced oscillation technique), collection of bronchoalveolar lavage fluid (BALF) and serum. '...' In contrast, 6-weeks of OVA challenges decreased Treg numbers back to control levels. Adoptive transfer of 1x106 Treg taken from DLN of 3-week challenged mice attenuated AHR in single-OVA recipients (p<0.05). Furthermore, in vivo depletion of Treg in 3-week OVA challenged mice restored AHR (p<0.05 compared with control). Similar proportions of CD4+ T cells became activated following both aerosol regimes, however total numbers of airway CD4+ T cells were decreased (p<0.05), and OVA-specific CD4+ T cell proliferation in DLN was reduced (p<0.05) after 3-weeks versus one OVA aerosol. Analysis of antigen handling by airway APC populations showed antigen uptake (OVA-647) and processing (DQ-OVA) by macrophages and airway DC subsets to be down-regulated (p<0.05) after 3-weeks of OVA aerosols. In addition, adoptive transfer of Treg into single-OVA recipients did not affect antigen handling by airway APC populations. These data suggest that Treg are responsible for allergen-induced attenuation of AHR in vivo in established airways disease. AHR attenuation was associated with an altered function of airway DC, resulting in reduced antigen capture and processing, leading to limited clonal expansion of antigen-specific CD4+ T cells with limited production of Th2 cytokines. Furthermore, Treg were not directly responsible for the down-regulation of allergen capture in the airways. In conclusion, knowledge of the role of Treg and DC in attenuation of AHR could potentially result in improved and more directed therapies for the attenuation of AHR in atopic asthmatics.

Abstract Early in the evolution of the vertebrates it is thought that two genomic duplications occurred, providing a basis for the evolution in body plan and neural crest of very early vertebrates and substantive material for further evolution of various gene families such as those making up a number of components of the adaptive vertebrate immune system. While the bony fish possibly had another, genome duplications are not generally a feature of vertebrate evolution and indeed the appearance of an antigen-adaptive immune recognition system may have served to limit the size that various vertebrate genomes, including that of the human, can in fact achieve. This initial step in vertebrate immune evolution, the establishment of recognition of non-self against the unique set of 'self' epitopes for an individual, provided an immensely powerful weapon in immune function with the ability to tailor a defense against as-yet-unseen dangers at any time albeit with the pitfall of autoimmune disease. As the recognition sites of the antigen receptor molecules such as TcR are produced by clonal modification of the segments provided in the germline and are thus not in the genome itself, pathogens have not been able to hijack this one component of the immune system in the way so many other components have been put to use throughout evolution, nor do these components necessarily reveal themselves as associated with disease through genome screens. Importantly, overall immune function is determined not just by the potential repertoire of recognition receptors but also by the ability of immunocompetent cells to migrate in a tissue specific fashion through the use of various chemokines and their receptors. Typical of the hijacking of an immune system component by a pathogen is the use of a chemokine ligand gene in the viral ancestor to SIV and HIV, allowing for virus binding to immunocompetent cells as is seen in the use of the CCR5 chemokine receptor by macrophage-tropic HIV strains. This thesis describes the allele and genotype frequencies for several TcR beta-chain variable segment polymorphisms in a population of MS patients compared with controls before and after stratification for HLA-DR15, polymorphism in the Apo-1 / Fas promoter, the DRB1 Val86/Val86 genotype, CCR5-delta32 and the HLA-DRA promoter. The thesis continues with CCR5-delta32 genotyping in IDDM, MS and SLE cohorts and then examines the question of the population of origin of the delta-32 allele of the CCR5 receptor for chemokine. Here, a case / control comparison of 122 RR-MS patients with 96 normal individuals was made for allele and genotype frequencies and for haplotypes formed by pairs of TCRB markers. Further analysis was made after HLA-DR15 stratification. Linkage disequilibrium was found between pairs of alleles of bv8s1, bv10s1, bv15s1 and bv3s1 loci in both patients and controls. In the RR-MS cohort, an increase in the allele frequency of bv8s1*2 was seen (p = 0.03) and the haplotype bv8s1*2 / bv3s1*1 was increased (p = 0.006), and both were found to be statistically significant. In the DR15-positive group, association between MS and TCRB was seen with the bv8s1*2 allele (p = 0.05) and the bv8s1*2 / bv10s1 haplotypes (p = 0.048), while the haplotype associations seen among the DR15-negative patients included the bv3s1*1 allele (bv10s1*1 / bv3s1*1, p = 0.022; bv8s1*2 / bv3s1*1, p = 0.048). While no associations were found after stratification for SDF1-3'A, Apo-1 / Fas or DRB1 there were modest interactions between bv3s1, bv10s1 and bv15s1 and the HLA-DRA promoter. These results support the involvement of the TCRB region in MS susceptibility. The further study of autoimmune disease here includes genotype analysis of CCR5-delta32 in type 1 diabetes (IDDM) and SLE. CCR5 is the major co-receptor for viral entry used by macrophage-tropic HIV strains and protection from infection is seen in homozygotes for CCR5-delta32. In diabetes, infiltration of pancreatic tissue by autoreactive T-cells involves secretion of multiple cytokines and chemokine receptor expression. Variation in the chemokine receptor CCR5 may result in differences in inflammatory cell migration in response to relevant chemokines. Adolescents with type 1 diabetes were genotyped for CCR5-delta32 (n = 626). The allele frequency was compared with that of 253 non-diabetic adolescents and with that of 92 adults with SLE. A reduced allele frequency was seen in type 1 diabetes compared with controls (0.092 vs 0.123, p = 0.05). This difference was not seen for the cohort of patients with SLE (freq = 0.114). A reduction in the number of CCR5-delta32/delta32 homozygotes, who lack CCR5, in the type 1 diabetes cohort was also seen and while not statistically significant (2 observed compared to 5.25 expected; p = 0.12) is interesting. These results suggest a partial protection from type 1 diabetes for CCR5-delta32 homozygous individuals is possible and that CCR5 has a potential role in the pathogenesis of type 1 diabetes. Global surveys of the CCR5-delta32 allele have confirmed a single mutation event in a Northeastern European population as the source of this allele. Here, Australian Ashkenazi Jews (n = 807) were found to have a CCR5-delta32 allele frequency of 14.6% while Australian Sephardic Jews (n = 35) had a frequency of 5.7% and non-Jewish Australian controls (n = 311) had an allele frequency of 11.25%. Data on birthplace of grandparents showed a gradient with highest CCR5-delta32 frequencies from Eastern European Ashkenazim (~19.5% for those whose four grandparents come only from Russia, Poland, Hungary, Austria and Czechoslovakia; n = 197) which differs significantly from the frequency seen in Ashkenazi Jews from Western Europe (n = 101, p = 0.001). Homozygotes for CCR5-delta32 were genotyped with 3p21 region microsatellites. This has defined an ancestral haplotype on which the mutation first occurred and helped to date this event to between 40 and 50 generations ago or just over a thousand years ago. The population gradient, combined with the dating of the mutation by microsatellite allele frequencies, suggests an origin for the CCR5-delta32 allele in a population ancestral to the Ashkenazim. The distribution in non-Jewish populations in northern Europe has led others to postulate spread of the mutation by Vikings. It is hypothesised here that the link between the two populations could be the kingdom of Khazaria with subsequent admixture into both Swedish Vikings and Ashkenazi Jews. The basic driving force of evolution is through selection and the immune system has a role which, through the survival pressure exerted by viruses and other pathogens, has the potential to exert a great deal of selective force on the various components of this system. The effects of this pronounced selection on an immune system component can be seen for example in the increase of the CCR5-delta32 allele over the last thousand years to the current frequency. As mentioned, some immune system components are not affected by such straightforward selection. In the case of the TCRBV segments, effects on the immune repertoire can occur through MHC interaction at the point of thymic entry and in the effects of various superantigens, but the actual binding pockets that recognise antigen are themselves unable to be selected for (or against). The findings presented in this thesis provide support for the association of TCRBV gene segments with multiple sclerosis and also provide support for the further study of the role of the CCR5-delta32 allele in type 1 diabetes. Furthermore, data presented here suggests that the CCR5-delta32 allele had an origin in the Khazar Kingdom just over a thousand years ago, accounting for the allele frequencies in both the Ashkenazi Jews and in lands frequented by the Vikings. The definition of an extended ancestral haplotype for the CCR5-delta32 allele shows how the effect of selection of an allele of one gene can carry with it specific alleles of a large number of other genes as well.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 176-216).