Thesis (M.S.P.H.)--University of Michigan, 1940.

Thesis (M.S.P.H.)--University of Michigan, 1940.

No description available.

Thesis--Wisconsin. / Includes bibliographical references (leaves 45-49).

No description available.

No description available.

Effective control of chronic viral infections may require the generation of polyfunctional T cells (PFCs) which are capable of producing multiple cytokines and possess cytotoxic function. In this study, I investigate (i) whether PFCs play an important role in the long term immune control of a persistent human virus, Epstein-Barr virus (EBV), (ii) the relationship between the development of immunodominance and functionality during the evolution of the anti-viral T cell responses, and (iii) whether PFCs can be generated in patients with EBV-associated haemophagocytic lymphohistiocytosis (HLH). To tackle the first question, I established a 9-color flow cytometry assay to characterize the co-expression of four cytokines (interferon-f [IFN-[], macrophage inflammatory protein 1-] [MIP1-[], tumour necrosis factor-] [TNF- ] and interleukin-2 [IL-2]) and degranulation marker (CD107a) by both EBV lytic and latent peptide-specific CD4+ and CD8+ T cells in 20 healthy long term viral carriers. Two patients with EBV-associated post-transplant lymphoproliferative disorder (PTLD) were studied for comparison. Both CD4+ and CD8+ PFCs were readily generated in the long term carriers with the immunodominant EBV proteins apparently stimulating higher proportions of PFCs than the subdominant viral proteins. The PFCs producing greater amount of cytokines per cell than the single functional T cells. In contrast, EBV-specific PFCs were hardly generated in the patients with PTLD. To investigate the relationship between the development of immunodominance and functionality, I performed a longitudinal study of CD4+ and CD8+ T cell responses in 10 children with infectious mononucleosis (IM) and 4 asymptomatic individuals (AS) with primary EBV infection from the time of diagnosis to one year post-infection. Viral peptide-specific T cells were examined for the co-expression of three cytokines (IFN-t, TNF-T and IL-2), perforin and CD107a upon stimulation with overlapping peptide pools of lytic and latent proteins, respectively. PBMC viral loads were reduced gradually in both IM and AS subjects. Whilst lytic and latent peptide-specific PFCs were still detectable at the acute stage of infection, they showed an increase in functionality over time in response to peptide pools of immunodominant proteins. From acute to persistent infection stage, the CD8+ T cell responses shifted from reactivities against the lytic peptides to those against the latent EBNA3A and 3B peptides with concurrent increase in functionality. Change in CD4+ T cell responses is less obvious, apparently from reactivities towards broad range to EBNA1 peptides. Finally, we found that two patients with the life-threatening EBV-associated haemophagocytic lymphohistiocytosis (HLH) had very high viral loads at the onset of disease. The clinical symptoms improved and viral loads were gradually reduced by the immunosuppressive drug therapy. Interestingly, EBV lytic and latent peptide-specific PFCs could be subsequently generated post-treatment with sustained resolution of clinical symptoms and clearance of plasma viral loads . In conclusion, lytic and latent peptide-specific CD4+ and CD8+ PFCs may confer long term immune control to EBV. The PFCs may be generated concurrent with the establishment of immunodominance hierarchy during the evolution of viral-specific T cell responses. Long term polyfunctional T cell responses to EBV can be formed in patients with EBV-associated HLH. / published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

Thesis (doctor of medicine)--Rijksuniversiteit te Groningen, 1979.

Thesis (Ph.D.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Public Health Sciences. Title from pdf file main screen (viewed on April 28, 2010). Includes bibliographical references.

Epstein-Barr virus (EBV) induced infectious mononucleosis (IM) is characterized by the activation and expansion of T lymphocytes and the induction of cytotoxic responses able to mediate the lysis of EBV-uninfected, allogeneic MHC mismatched and EBV-infected autologous target cells. Freshly isolated peripheral blood mononuclear cells (PBMC) were used to examine the nature of these cellular immune responses. Activated lymphocytes, as identified by HLA-DR expression, associated with EBV induced IM were shown to be a heterogeneous population containing significantly elevated cytotoxic/suppressor (CD8+) T cells, helper/inducer (CD4+) T cells and natural killer (NK, CD16+) cells. CD8+ T cells were the primary activated population, representing 24% of the total lymphocyte population and 60-70% of the CD8+ T cell population. The activated CD4+ T cells and natural killer (NK) cells accounted for 7% and 4% of the total lymphocyte population, respectively. Analysis of serum soluble interleukin 2 receptors (IL-2R) and CD8 molecules demonstrated significantly (p<0.001) elevated levels in the sera of IM patients compared with normal controls. These elevated levels of serum IL-2R am CD8 molecules correlated, (r=0. 67 and r=0.82, respectively) with increased percentages of CD8/HLA-DR positive T cells (i.e., activated CD8 T cells). Increased levels of soluble cell surface molecules peaked during the acute phase and normalized as the patients progressed toward convalescence. Individual patients demonstrated strong correlations between the percentage of CD8/HLA-DR positive cells and soluble CD8 levels. The functional significance of the serum IL-2R and CD8 molecules is presently unknown. However, the strong correlative data between serum CD8, and to a lesser extent IL-2R, and CD8 T cell activation suggests that serum CD8 levels may provide a sensitive measure of CD8 T cell activation in systemic infections. The ability of freshly isolated acute IM PBMC to lyse allogeneic, EBV-infected lymphoblastoid cell lines (LCL), demonstrated the ability of acute IM effector cells to lyse MHC mismatched target cells. Effector cells from acute IM patients lysed allogeneic DM-LCL and AF-LCL target cells by 34% (n=7) and 23% (n=6), respectively, compared with 4% (n=5) and 0% (n=5), respectively, for normal controls. MAb-dependent complement depletion of CD3+ or CD8+ cells with anti-CD3 and anti-CD8 mAb decreased the non-MHC restricted cytolysis of LCL by 96% and 89%, respectively. In contrast, complement depletion with NK-cell specific mAbs Leu 11b and NKH-1, resulted in only a slight decrease (<35%) in the lysis of these LCL (46%). Depletion with anti-HLA-DR also significantly (p<0.001) decreased the lysis of LCL. Depletions with anti-CD4 demonstrated no decrease in LCL-lysis. MAbs OKT3 and OKT8 inhibited the non-MHC restricted cytolysis by 87% and 82%, respectively. We interpret these results as evidence that, 1) lysis of allogeneic cells is mediated primarily by CD3+, CD8+, HLA-DR+, cytotoxic T lymphocytes (CTL); and 2) these acute IM cytotoxic T cells utilize the T cell receptor and the CD8 antigen as an accessory molecule. An active role for target cell MHC class I molecules in the recognition and subsequent lysis of target cells is supported by a number of observations: 1) the MHC class I reactive mAbs W6/32 and BBM.1 significantly (p<0.05) inhibited the lysis of 63463-LCL by 65% and 57%, respectively; 2) acute IM effector T cells did not lyse the MHC class I negative Daudi cell line; 3) allogeneic MHC class I matched LCL mediated strong competitive inhibition (72% at 10:1 competitor to target cell ratio) vs 29% competitive inhibition for an allogeneic MHC class I mismatched LCL; and 4) NK-cell depleted effector cells from one patient mediated preferential lysis of the K562 cell line expressing MHC class I. HLA-A2 molecules. We interpret these results as evidence that target cell MHC class I molecules (or associated determinants) are the target antigen(s) for the allogeneic MHC cytotoxic response. The role of EBV in this acute allogeneic response was examined using target cell lines devoid of EBV genome. Acute IM CTL mediated lysis of the allogeneic HSB-2 T cell line (45%), and allogeneic HTLV-I transformed T cell lines (16%). The lysis of the HSB-2 T cell line was inhibited by anti-OKT3 (58% inhibition), W6/32 (53%) and BBM.1 (42%). Similarily, lysis of HTLV-I T cell lines was inhibited by W6/32 (69% inhibition), BBM.1 (69%) and OKT3 (38%). These data demonstrate that EBV antigenic expression is not required for allogeneic recognition and subsequent lysis of these allogeneic target cells. Effector cells from acute IM patients (n=5) were able to lyse their autologous EBV-infected LCL (mean lysis=21%), but were unable to lyse the EBV-uninfected autologous HTLV-I T cell line. These same effectors, however, were able to mediate lysis of both allogeneic B cell lines (21% lysis) and allogeneic T cell lines (8% lysis). These data are consistent with the observations by Strang et al. (1987a), who recently cloned virus specific/MHC-restricted CTL cloned from acute IM PBMC. These virus specific/MHC-restricted T cells presumably mediate the lysis of the autologous EBV-transformed B cell lines but not the autologous EBV-uninfected T cell lines. Whether the CTL which lyse the autologous EBV-transformed LCL are also responsible for the observed allogeneic reactivity was examined with cold target competition using autologous and allogeneic LCL. Lysis of autologous LCL was inhibited only by autologous competitor cells (64% inhibition compared with 24% for allogeneic LCL). Likewise, lysis of the allogeneic LCL was inhibited only by the allogeneic competitor cells (85% inhibition compared with 30% for autologous LCL). These data demonstrated no competition between allogeneic and autologous LCL and therefore support the concept that lysis of autologous LCL and allogeneic target cells is mediated by distinct effector populations. These data help us to understand the unusual immune response observed during acute IM. The strong allogeneic cytotoxic response is thought to represent polyclonal CD8 T cell activities induced by EBV-infected and transformed B cells which circulate in vivo. In addition, a population of CD8 CTL exist which mediate the lysis of autologous EBV-transformed B cells. These CTL likely represent virus-specific/MHC-restricted CTL and presumably play a major role in the control of EBV infections. The role, if any, of the markedly expanded alloreactive CTL population in the elimination of EBV infected and transformed B cells remains to be clarified.