Phenotype and Function of CD25-Expressing B Lymphocytes Isolated from Human Umbilical Cord Blood

Background. We have shown that approximately 30% of human peripheral blood B-cells express CD25. B cells expressing CD25 display a mature phenotype belonging to the memory B-cell population and have a better proliferative and antigen-presenting capacity. The aim of the present study was to characterize the CD25-expressing subset of B cells in human cord blood. Material and Methods. Mononuclear cell fraction from human cord blood (n = 34) and peripheral adult blood (n = 22) was sorted into CD20+CD25+ and CD20+CD25− B-cell populations. Phenotype and function of these B-cell populations were compared using flow cytometry, proliferation, cytokine production, and immunoglobulin secretion. Results. CD25-expressing B cells are a limited population of cord blood mononuclear cells representing 5% of the CD20+ B cells. They are characterised by high expression of CD5 in cord blood and CD27 in adult blood. CD25-expressing B cells express a functional IL-2 receptor and high levels of CC-chemokine receptors and spontaneously produce antibodies of IgG and IgM subclass. Conclusions. CD25 expression is a common denominator of a specific immunomodulatory B-cell subset ready to proliferate upon IL-2 stimulation, possibly ready to migrate and home into the peripheral tissue for further differentiation/action

Short- and long-term effects of anti-CD20 treatment on B cell ontogeny in bone marrow of patients with rheumatoid arthritis

It has been known for a long time that B cells play a role in rheumatoid arthritis (RA). By production of autoantibodies, presentation of auto-antigens and by producing cytokines B cells may contribute to the pathogenesis of RA. In recent years it has been shown that anti-B cell therapy is a powerful tool in the treatment of RA. The aim of this thesis was to a) investigate the effect on B cell ontogeny following B cell depletion therapy, b) during B cell depletion therapy evaluate serological and humoral immune responses and finally, c) try to establish a connection between Epstein-Barr virus (EBV) infection, CD25+ B cells and outcome of B cell deletion therapy. In paper I we could show that in bone marrow of RA patients following anti-CD20 treatment with rituximab (RTX) IgD expressing naïve cells are depleted whereas immature and memory B cells where still detectable. However, the long-term effects clearly showed a reduction of memory B cells in bone marrow. The examination of rheumatoid factor (RF) production revealed that RFs decline short after treatment but returned to baseline levels concurrently with the IgD expressing B cells when patients where subjected to an additional course. In paper II the cellular and humoral immune responses were evaluated by immunisation of RA patients before or during RTX treatment with a protein vaccine against influenza and a pneumococcal polysaccharide vaccine. The results suggest that both cellular and humoral immune responses are affected in patients receiving RTX treatment and we therefore suggest that immunisation should be performed before RTX treatment. In paper III we investigate the effects of EBV on selected B cell subsets and how infection may affect the clinical response to RTX treatment. The phenotypical study showed that B cells are more mature in EBV infected patients and the CD25+ B cell subset was more mature as compared to the CD25- B cell population. The evaluation of clinical response to RTX treatment with regard to B cell subsets showed that non-responding EBV+ patients had a significantly larger CD25+ plasma cell population. When investigating the effects of EBV stimulation in vitro we found that the CD25+ B cell population developed into antibody-producing cells to a higher extent than did the corresponding CD25- B cell population. The results of our studies indicate that that B cells play an essential role in the pathogenesis of RA. During RTX treatment we suggest that the IgD expressing population may harbour the autoantibody producing B cells. We also claim that that there are subsets of B cells (i.e. CD25+ B cells) that may have significant impact on the pathogenesis of RA, and the clinical outcome following RTX treatment

Mice Chronically Fed High-Fat Diet Have Increased Mortality and Disturbed Immune Response in Sepsis

BACKGROUND: Sepsis is a potentially deadly disease that often is caused by gram-positive bacteria, in particular Staphylococcus aureus (S. aureus). As there are few effective therapies for sepsis, increased basic knowledge about factors predisposing is needed. METHODOLOGY/PRINCIPAL FINDINGS: The purpose of this study was to study the effect of Western diet on mortality induced by intravenous S. aureus inoculation and the immune functions before and after bacterial inoculation. Here we show that C57Bl/6 mice on high-fat diet (HFD) for 8 weeks, like genetically obese Ob/Ob mice on low-fat diet (LFD), have increased mortality during S. aureus-induced sepsis compared with LFD-fed C57Bl/6 controls. Bacterial load in the kidneys 5-7 days after inoculation was increased 10-fold in HFD-fed compared with LFD-fed mice. At that time, HFD-fed mice had increased serum levels and fat mRNA expression of the immune suppressing cytokines interleukin-1 receptor antagonist (IL-1Ra) and IL-10 compared with LFD-fed mice. In addition, HFD-fed mice had increased serum levels of the pro-inflammatory IL-1beta. Also, HFD-fed mice with and without infection had increased levels of macrophages in fat. The proportion and function of phagocytosing granulocytes, and the production of reactive oxygen species (ROS) by peritoneal lavage cells were decreased in HFD-fed compared with LFD-fed mice. CONCLUSIONS: Our findings imply that chronic HFD disturb several innate immune functions in mice, and impairs the ability to clear S. aureus and survive sepsis

Epstein–Barr virus in bone marrow of rheumatoid arthritis patients predicts response to rituximab treatment

Objectives. Viruses may contribute to RA. This prompted us to monitor viral load and response to anti-CD20 therapy in RA patients

Helicobacter pylori Induces Transendothelial Migration of Activated Memory T Cells

Helicobacter pylori infection is associated with pronounced infiltration of granulocytes and lymphocytes into the gastric mucosa, resulting in active chronic gastritis that may develop into duodenal ulcer disease or gastric adenocarcinoma. Infiltrating T cells play a major role in the pathology of these diseases, but the signals involved in recruitment of T cells from blood to H. pylori-infected tissues are not well understood. We therefore examined H. pylori-induced T-cell transendothelial migration (TEM). The Transwell system, employing a monolayer of human umbilical vein endothelial cells, was used as a model to study TEM. H. pylori induced a significant T-cell migration, compared to spontaneous migration. CD4(+) and CD8(+) T cells migrated to the same extent in response to H. pylori, whereas there was significantly larger transmigration of memory T cells compared to naive T cells. Both H. pylori culture filtrate and urease induced migration, and the presence of the H. pylori cag pathogenicity island increased TEM. T-cell TEM was mediated by LFA-1-ICAM-1 interactions in accordance with an increased ICAM-1 expression on the endothelial cells after contact with H. pylori. Migrating T cells had increased expression of activation marker CD69 and chemokine receptors CXCR3, CCR4, and CCR9. Furthermore, T cells migrating in response to H. pylori secreted Th1 but not Th2 cytokines upon stimulation. In conclusion, our data indicate that live H. pylori and its secreted products contribute to T-cell recruitment to the gastric mucosa and that the responding T cells have an activated memory Th1 phenotype