B-lymphocyte

When B lymphocytes are stimulated by antigen they develop into plasma cells. The receptor of plasma cells can be secreted from the cell because some of these molecules lack the hydrophobic domain that normally anchors the receptor to the plasma membrane. These secreted molecules are immunoglobulins or antibodies and have a common structure (Fig. 1.8). They are found in a variety of bodily fluids and in many tissues. 

Neutrophils and host defence The fight against infection 

B cells are one of the two major types of lymphocytes. These bone marrow derived cells express a cell-surface immunoglobulin, also referred to as a B cell receptor. Upon activation by antigen, these cells differentiate into plasma cells and produce antibodies of the same type as their receptor [26]. 

However, B cells are also capable of expressing other chemokine receptors than previously mentioned. Studies have demonstrated that B cells can also express CC R1, CCR2, CCR5, CCR6, CCR8 CCRIO and CXCR3 (4, 11, 15-18, 28]. 

B cells can produce several chemokines. After stimulation, they can release CCLl 5, CCL22, CXCL14 and CXCL16 [4, 5]. 

T cells are bone marro v-derived lymphocytes. There are six different types of Tcells identified in humans helper T cells (Th), cytotoxic T cells (Tc), memory T cells, regulatory T cells (Treg), natural killer T cells (NKT) and yb T cells. AD types have different roles in the adaptive immune systems and consequentiaUy distinct chemokine receptor expression patterns. 

Memory CD4 and CD8 T cells can be divided in effector and central memory Tcells. Effector memory cells are thought to home to nonlymphoid tissues, whereas the central memory T cells localize more to secondary lymphoid tissue [29]. Although originally distinguished by the expression of CCR7 by the central memory T cells, it is clear that both subsets express CCR7 [29, 34]. However, it is thought that these memory cells can express every appropriate chemokine receptor [29]. 

After maturation in the bone marrow, B lymphocytes home into secondary lymphoid tissues, such as lymph nodes, from which they are soon released into the circulation, or move through different areas while undergoing a final differentiation (3). The chemokine receptor CXCR5 may be involved in B-lymphocyte entry into the B-lymphocyte-rich follicles. CXCR5 is expressed on the surface of mature circulating B lymphocytes (3,35,60). Its ligand, CXCL13, is constitutively expressed within the follicles (2,3,61). 

Deletion of the CXCR5 gene yields a phenotype in which the animals do not develop inguinal lymph nodes and do develop defective follicles and germinal centers in the spleen and Peyer s patches (3,41). Receptor-deficient B lymphocytes are able to migrate into T-lymphocyte-rich peripheral and interfollicular areas, but are unable to migrate farther, into the deeper B-lymphocyte-rich follicles (3). 

absent in immature B cells, is expressed when maturation is complete and cells are ready to leave the bone marrow, and it is down-regulated after terminal differentiation (3,62). Lymphotoxin, a member of the tumor necrosis factor family, appears to be important for optimal expression of CXCL13 during development (36,37). 

This hypothesis remains controversial, however, because it is clear that B lymphocytes are not as dependent as T lymphocytes on CCL21 for entry into 

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Another example of vims clearance is for IgM human antibodies derived from human B lymphocyte cell lines where the steps are precipitation, size exclusion using nucleases, and anion-exchange chromatography (24). A second sequence consists of cation-exchange, hydroxylapatite, and immunoaffinity chromatographies. Each three-step sequence utilizes steps based on different properties. The first sequence employs solubiUty, size, and anion selectivity the second sequence is based on cation selectivity, adsorption, and selective recognition based on an anti-u chain IgG (24). 

The adaptive or specific arm of the immune system consists of T- and B-lymphocytes and antibodies. T- and... 

An allergen is usually an inert substance (e.g. pollen, house dust mite faeces) that in some individuals can trigger the generation of an (inappropriate) antigenic response. Mediated by TH2 lymphocytes, it causes B-Lymphocytes to produce lgE. Subsequent exposure of a sensitized individual to the allergen is therefore able to cross-link IgE antibodies on the surface of mast cells and trigger an immune response and histamine release. 

An antigen is a molecule recognised by specific receptors on cells of the immune system such as B lymphocytes. 

T- or B-lymphocytes which react with autoantigens. In healthy individuals kept under control by the mechanisms of self tolerance. 

A B lymphocyte is a specific type of white blood cell (leucocyte) derived from bone marrow stem cells. Each B lymphocyte expresses an immunoglobulin (antibody) specific for a particular antigen. Following antigenic stimulation, a B lymphocyte may differentiate and multiply into plasma cells that secrete large quantities of monoclonal antibody. 

CpG stands for cytosine phosphate guanine dinucleotide in a particular sequence context. CpG motifs are responsible for proliferative effects of antisense oligonucleotides, particularly with respect to B-lymphocytes. Die optimal immune-stimulatory consensus sequence surrounding CpG is R1R2CGY1Y2, where R1 is a purine (mild preference for G), R2 is a purine or T (preference for A), and Y1 and Y2 are pyrimidines (preference for T). 

Monoclonal antibodies (mAh) are molecules that recognize and bind a specific foreign substance called an antigen. They are produced from a single clone of B lymphocytes. Conventionally, mouse mAh have been generated for experimental and diagnostic use. Techniques have been developed to humanize mouse mAh to facilitate their therapeutic use in humans. It is also now possible to make mAh which are fully human. 

Cellular Components of Adaptive Immune Responses are T- and B-Lymphocytes whereas Humoral Components are Antibodies. 

The hallmark of T- and B-lymphocytes is that each single lymphocyte expresses antigen receptors of a single specificity that was created randomly during the development of that individual lymphocyte. This is achieved mainly by sequential genetic rearrangement... 

Immune Defense. Figure 2 Cytokines involved in the development of adaptive immune responses in secondary lympoid tissues such as the lymph nodes or spleen. Abbreviations B B-lymphocyte, IFN interferon, Ig immunoglobulin, IL interleukin, NK natural killer cell, TE T-effector (cytotoxic) lymphocyte, TH T-helper lymphocyte... 

A cytokine, secreted by TH2-cells, stimulates B-cells in different stages of their development. It may act as a growth factor or as a differentiation factor, causing B-lymphocytes to switch antibody to IgE. In T-cells it causes differentiation into TH2-cells. 

A lipopolysaccharide (LPS) is any compound consisting of covalently linked lipids and polysaccharides. The term is used more frequently to denote a cell wall component from Gram-negative bacteria. LPS has endotoxin activities and is a polyclonal stimulator of B-lymphocytes. 

Lymphocytes are specialized white blood cells that play a crucial role in an immune response.They can be T lymphocytes, which can directly target and destroy defective cells, or B lymphocytes, which produce antibodies directed against specific antigens. Both T and B lymphocytes produce a variety of cytokines to augment and amplify the immune response. 

Multiple scelerosis is an autoimmune disease mediated by T and B lymphocytes and macrophages. This is characterized by extensive inflammation and demyelination of the myelin sheath that surrounds the nerve fiber. The death of the nerve fiber results in a variety of symptoms that can lead to impairment of movement, paralysis, and death. 

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