Bibliography: leaves 287-310 / 311 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Dept. of Paediatrics, 1991

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Undergraduate honors paper--Mount Holyoke College, 2006. Dept. of Biological Sciences. / Includes bibliographical references (leaves 80-84).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 122-137).

Intravenous immunoglobulin (IVIg) has been used to treat a variety of autoimmune disorders including multiple sclerosis (MS); however, its mechanism of action remains elusive. Our results demonstrate a novel finding wherein IVIg treatment induces a dramatic surge (>1000-fold increase) in the levels of IL-11 in the circulation and that the liver is the organ of increased IL-11 transcription. Furthermore, we show that IL-11Rα knockout mice, although initially protected, become resistant to protection by IVIg during experimental autoimmune encephalomyelitis (EAE) and develop disease with a similar incidence and severity as control-treated IL-11Rα-/- mice. The inability of IVIg to prevent EAE in IL-11Rα-/- mice correlated with a failure of this agent to decrease IL-17 production by myelin-reactive T-cells in the draining lymph nodes. Finally, we show that IL-11 can directly inhibit IL-17 production by lymph node cells in culture. Together, these results implicate IL-11 as an important immune effector of IVIg in the amelioration of EAE.

Intravenous immunoglobulin (IVIg) has been used to treat a variety of autoimmune disorders including multiple sclerosis (MS); however, its mechanism of action remains elusive. Our results demonstrate a novel finding wherein IVIg treatment induces a dramatic surge (>1000-fold increase) in the levels of IL-11 in the circulation and that the liver is the organ of increased IL-11 transcription. Furthermore, we show that IL-11Rα knockout mice, although initially protected, become resistant to protection by IVIg during experimental autoimmune encephalomyelitis (EAE) and develop disease with a similar incidence and severity as control-treated IL-11Rα-/- mice. The inability of IVIg to prevent EAE in IL-11Rα-/- mice correlated with a failure of this agent to decrease IL-17 production by myelin-reactive T-cells in the draining lymph nodes. Finally, we show that IL-11 can directly inhibit IL-17 production by lymph node cells in culture. Together, these results implicate IL-11 as an important immune effector of IVIg in the amelioration of EAE.

Spinal cord injury (SCI) is a devastating condition that causes its victims to experience functional deficits. Inflammation plays a complex role in the progression of SCI. While some inflammatory cells attenuate further damage to the spinal cord tissue, other inflammatory mediators exacerbate the damage. Attenuating the detrimental aspects of inflammation after SCI is an attractive neuroprotective strategy that could potentially lead to significant functional improvement. In this regard, intravenous immunoglobulin G (IgG), which has many proposed immuno-modulatory mechanisms, is a potential treatment candidate. In this study, we investigated the neuroprotective properties of IgG by examining its effects after SCI at the molecular, cellular, and neurobehavioral levels. We observed that IgG treatment after SCI is associated with significant reduction in pro-inflammatory mediators and significant improvement in neurobehavioral recovery compared to the control. The results of the study suggest that IgG could potentially be used as an immuno-modulatory therapy for SCI.

Spinal cord injury (SCI) is a devastating condition that causes its victims to experience functional deficits. Inflammation plays a complex role in the progression of SCI. While some inflammatory cells attenuate further damage to the spinal cord tissue, other inflammatory mediators exacerbate the damage. Attenuating the detrimental aspects of inflammation after SCI is an attractive neuroprotective strategy that could potentially lead to significant functional improvement. In this regard, intravenous immunoglobulin G (IgG), which has many proposed immuno-modulatory mechanisms, is a potential treatment candidate. In this study, we investigated the neuroprotective properties of IgG by examining its effects after SCI at the molecular, cellular, and neurobehavioral levels. We observed that IgG treatment after SCI is associated with significant reduction in pro-inflammatory mediators and significant improvement in neurobehavioral recovery compared to the control. The results of the study suggest that IgG could potentially be used as an immuno-modulatory therapy for SCI.

Antigens play a critical role in the development of chronic lymphocytic leukemia (CLL) by binding to and stimulating leukemic precursor cells at some point during CLL ontogeny. Nevertheless, much remains unknown and further studies are necessary before an accurate model of antigen-drive can be ascertained. In this context, intraclonal diversification (ID) analysis of immunoglobulin (IG) genes could shed light on whether antigen involvement is restricted to the malignant transformation phase or if the triggering antigen(s) continuously stimulates the CLL clone. Hence, in Paper I we conducted a large-scale analysis of 71 CLL cases and revealed that 28/71 cases carried intraclonally diversified IGHV-IGHD-IGHJ genes. Although most cases showed no or low levels of ID, intense ID was evident within all subset #4 (IGHV4-34/IGKV2-30) cases. Subsequent analysis, in Paper II, of the clonotypic light chains revealed that the outstanding exception again related to subset #4. In such cases, the expressed IGKV2-30 gene was affected by targeted ID, analogous to their partner IGHV4-34 gene. Whilst these results convincingly argued for the role of antigen(s) in the development and evolution of CLL subset #4, this analysis was limited to depicting what was occurring at a single time-point and could not provide insight into the temporal dynamics of the CLL clones. Thus, in Paper III we conducted a longitudinal study of 8 subset #4 cases which enabled us to establish a hierarchical pattern of subclonal evolution. The observed ‘stepwise’ accumulation of mutations strongly supports a role for antigen selection in the pathogenesis of CLL subset #4. In Paper IV we reported a subset of IgG-switched CLL patients with coexisting trisomies of 12 and 19, and propose that the emergence of trisomy 18 in such cases represents a clonal evolution event suggestive of selection due to a clonal advantage. Paper V focused on the IGHV3-21 gene, an adverse prognostic factor in CLL. Since ~60% of IGHV3-21-expressing cases carry stereotyped B cell receptors, recognition of a common antigenic epitope, perhaps of pathogenic significance, is envisaged. Therefore, we investigated IGHV3-21 gene frequency within a Swedish population-based cohort and assessed the impact of stereotypy on clinical outcome. Taken collectively, this thesis provides molecular and genetic evidence for the role of antigen in CLL pathogenesis by convincingly demonstrating that clonal evolution, at least for certain subsets of CLL, is functionally driven rather than a consequence of clonal expansion promoted by nonspecific stimuli.

The Leukocyte Immunoglobulin-like Receptors (LILRs) are a family of receptors that is broadly expressed on all leukocytes and have the ability to regulate their function. A substantial amount of evidence suggests that LILRs may be involved in immune homeostasis but also immune dysregulation. We therefore studied the role of LILRs in relation to the autoimmune disease, rheumatoid arthritis (RA). RA is a chronic and systemic inflammatory disease involving inflammation of the joints affecting the synovial membrane, cartilage and bone. Much of the tissue damage is a result of an inappropriate immune response within the joint space caused by the unwarranted activation of leukocytes. Here were report that LILRA2 (an activating receptor) that has been previously shown to be highly expressed in the rheumatoid synovium, induces the production of pro-inflammatory cytokines TNF-α, IL-1, IL-6, IFN-γ and IL-10 in primary monocytes. These cytokines are known to have an important role in the pathogenesis of RA indicating a pathway by which LILRA2 exacerbates RA. Co-ligation of LILRB4 (an inhibitory receptor) with LILRA2 abolishes cytokine production suggesting that LILRB4 is able to suppress the function of LILRA2. Expression of both LILRA2 and LILRB4 are regulated by inflammatory cytokines and LPS, indicative of a feedback mechanism. There is also cross-talk between LILRs and TLR4 as co-stimulation with LPS and either LILRA2 or LILRB4 inhibits cytokine production. A differential expression of LILRs has also been identified on lymphocytes of patients with RA whereby an increase of LILRA1 (activating) and LILRB1 (inhibitory) expressing circulating lymphocytes is present in RA patients when compared to healthy control subjects. From these studies, we propose that LILRs have a functional role in RA by regulating local and systemic inflammation. The presence of LILRA2 in the RA joint is detrimental since its potent ability to induce inflammatory cytokines, particularly TNF-α, can initiate leukocyte recruitment and activation of proteases. Along with TLR4, LILRA2 and LILRB4 have the potential to moderate the innate immune system via regulation of cytokine production. Furthermore, suppression of LILRA2 function may serve as a therapeutic tool in many inflammatory diseases.