This thesis describes the characterisation of citrullinated antigen-specific B cells in patients with rheumatoid arthritis (RA). These cells express and secrete anti-citrullinated protein... Show moreThis thesis describes the characterisation of citrullinated antigen-specific B cells in patients with rheumatoid arthritis (RA). These cells express and secrete anti-citrullinated protein antibodies (ACPA), which represent the most specific autoantibody system in RA. We started out by identifying ACPA-producing B cells in peripheral blood. FACS sort followed by culture showed that these cells are not confined to the memory B cell subpopulation, as circulating plasmablasts/cells were found that spontaneously produced ACPA in culture (chapter 2). Further characterisation showed an increased frequency of ACPA-secreting plasma cells in synovial fluid (SF), i.e. at the site of inflammation, which harbours the capacity to form a survival niche in culture that promotes sustained (auto-)antibody production (chapter 3). Next, ACPA-expressing B cells were identified directly after isolation using a streptavidin tetramer-based flow cytometry staining technique developed in chapter 4. Furthermore, we provided evidence for altered development of ACPA-producing B cells, as these cells were found to express lambda light chains (LC) more frequently than non-autoreactive B cells (chapter 5). Finally, we investigated CD28 expression on ACPA-expressing B cells and total B cells in RA patients as relevant molecule for an enhanced live span of long-lived plasma cells (chapter 6). Show less
Wentink, M.; Dalm, V.; Lankester, A.C.; Schouwenburg, P.A. van; Scholvinck, L.; Kalina, T.; ... ; Burg, M. van der 2017
The human herpesvirus Epstein-Barr virus (EBV) is a large DNA virus that infects over 90% of the adult world population. EBV is the causative agent of infectious mononucleosis and EBV infection is... Show moreThe human herpesvirus Epstein-Barr virus (EBV) is a large DNA virus that infects over 90% of the adult world population. EBV is the causative agent of infectious mononucleosis and EBV infection is associated with various malignancies. EBV establishes lifelong infections in immunocompetent hosts. To counteract the host’s immune defence, EBV acquired numerous immune evasion mechanisms. During latency of EBV, viral protein synthesis is limited or absent, making the virus-infected cells virtually invisible to the immune system. Evasion mechanisms of EBV active during primary infection as well as in reactivation are necessary for establishment of latent infection and prolonged replication. Studying viral evasion not only helps to understand EBV, but also the human immune system. Viral molecules interfering with antigen presentation by HLA I and HLA II have been identified previously, but so far, it was unclear how EBV interferes with the lipid antigen-presenting molecule CD1d. The work described in this thesis shows EBV’s mechanism to interfere with cell surface expression of CD1d. Further, a novel immune evasion molecule that obstructs antigen-presentation during the late lytic phase of EBV infection was identified and its working mechanism was unravelled. Understanding viral immune evasion mechanisms may aid in developing therapies for EBV-associated diseases. Show less
Seasonal influenza epidemics lead to severe flu in 3 to 5 million individuals and emerging pandemic influenza strains pose an even greater threat to society. We describe a clinical trial in which... Show moreSeasonal influenza epidemics lead to severe flu in 3 to 5 million individuals and emerging pandemic influenza strains pose an even greater threat to society. We describe a clinical trial in which vaccine-specific responses were measured during two consecutive influenza seasons, including the season in which the 2009 pandemic virus emerged, and showed that these vaccines induced both humoral and cellular responses. However, these responses are unlikely to be protective against newly emerging strains, due to the variable nature of influenza virus. Therefore, the other chapters in this thesis describe concepts within peptide-based vaccination strategies, which is one method to induce responses to highly conserved sequences of influenza virus. We evaluated a concept based on long peptides directed to highly conserved B and T cell epitopes and showed that this vaccine was capable of inducing both humoral and cellular immune responses. Furthermore, the vaccine provided partial protection against infection in an animal model. We also described another successful strategy to enhance the immunogenicity of minimal peptides by modification of these peptides and proceeded with formulations to improve delivery of these minimal peptides. Altogether, the findings in this thesis may contribute to the development of the next generation influenza vaccines. Show less
Antibody-mediated rejection is increasingly recognised within the transplantation community as a cause or contributing factor in the rejection of transplanted organs. The humoral immune response... Show moreAntibody-mediated rejection is increasingly recognised within the transplantation community as a cause or contributing factor in the rejection of transplanted organs. The humoral immune response towards allografts involves B cells that, after T cell dependent activation, can differentiate into antibody producing cells. Whereas there are several therapeutic entities to treat cellular rejection, at present, no standard treatment for humoral rejection exists. The first part of this thesis describes the effects of different maintenance immunosuppressive drugs directly on B cells, as well as the effect on T cell help in vitro. The data presented in these chapters show differential effects of the drugs on B cells and T cell help. Furthermore, the effects of novel, experimental drugs on the in vitro activation of B cells are described. The second part of this thesis describes the development of a novel technique for monitoring the humoral alloimmune response. By using this technique, patients at risk for humoral rejection may be identified. The last part describes the difficulties and pitfalls of monitoring T cells that respond to alloantigen via the indirect pathway of allorecognition. In an alloimmune response, these are the T cells that provide help to B cells to become fully activated. Show less
MHC class II antigen presentation by B cells is important to activate CD4+ T cells that stimulate the B cell to produce antibodies. Besides this, disruption of MHC class II antigen presentation... Show moreMHC class II antigen presentation by B cells is important to activate CD4+ T cells that stimulate the B cell to produce antibodies. Besides this, disruption of MHC class II antigen presentation could play a role in immune escape by tumor cells. This thesis describes MHC class II antigen presentation by B cells during bacterial infections and leukemia. We show that, in contrast to the current dogma, human B cells are able to phagocytose whole, living Salmonella bacteria via their B cell receptor (BCR). Salmonella survives intracellular and is transported by the B cell to the spleen where Salmonella can infect other cells. Although Salmonella uses the B cell to disseminate and escape the immune system, uptake of Salmonella by B cells also results in a good immune response consisting of specific antibody production, antigen presentation and activation of both CD4+ T helper cells and cytotoxic CD8+ T cells that are able to eliminate infected cells. Many leukemic cells express MHC class II. For AML (acute myeloid leukemia) we show that expression of the self-peptide CLIP could be a measure for immune escape because a high percentage of HLA-DR+/CLIP- blasts correlates with a longer disease-free survival. In B-CLL (chronic lymphocytic leukemia), the percentage of activated CD4+ and CD8+ T cells is enhanced and inversely correlated to CLIP. In addition, transcription of all MHC class II genes is increased and B-CLL patients with high HLA-DOA mRNA levels have a less favorable prognosis. Show less
UVA 1 therapy is a relatively new form of light therapy for atopic dermatitis. We describe that after 4 weeks of UVA-1 patients were better capable to maintain clinical improvement than after 3... Show moreUVA 1 therapy is a relatively new form of light therapy for atopic dermatitis. We describe that after 4 weeks of UVA-1 patients were better capable to maintain clinical improvement than after 3 weeks of therapy. Furthermore, UVA 1 therapy proved to be better than placebo therapy in patients with dyshidrotic eczema. Also, we described the favorable effect of UVA 1 therapy in chronic, generalized lichen ruber planus. Because of deep penetration of UVA 1, it could not only influence dermal inflammatory infiltrates in T-cell mediated diseases mentioned above, but also reach circulating activated B-cells in dermal capillaries in SLE. We investigated the effect of 6 and 12 J/cm2 UVA 1 in SLE patients, in a double-blinded, placebo-controlled, cross over study. Three weeks of 12 J/cm2 resulted in improved disease activity and proved to be more effective than placebo. Furthermore, a decrease of auto-antibody titers was observed in several patients. In vitro we showed that 40% of UVA 1 reached the dermis and increasing numbers of PBMCs died after rising doses of UVA-1. Also, immunoglobulin production by activated B cells decreased after increasing doses of UVA 1. It would be interesting to investigate UVA 1 therapy for other auto immune diseases. Show less
