B cell

(noun)

a lymphocyte, developed in the bursa of birds and the bone marrow of other animals, that produces antibodies and is responsible for the immune system.

Related Terms

Examples of B cell in the following topics:

  • Making Memory B Cells

    • Memory B cells are a B cell sub-type that are formed following primary infection.
    • Memory B cells are a B cell sub-type that are formed following a primary infection .
    • Most of them differentiate into the plasma cells, also called effector B cells (which produce the antibodies) and clear away with the resolution of infection.
    • To understand the events taking place, it is important to appreciate that the antibody molecules present on a clone (a group of genetically identical cells) of B cells have a unique paratope (the sequence of amino acids that binds to the epitope on an antigen).
    • B lymphocytes are the cells of the immune system that make antibodies to invading pathogens like viruses.

  • Cell-Mediated Autoimmune Reactions

    • A normal immune response is assumed to involve B and T cell responses to the same antigen, where B cells recognize conformations on the surface of a molecule for B cells, and T cells recognize pre-processed peptide fragments of proteins for T cells.
    • Roosnek and Lanzavecchia showed that B cells recognizing IgGFc could get help from any T cell that responds to an antigen co-endocytosed with IgG by the B cell as part of an immune complex.
    • Together with the concept of T cell-B cell discordance, this idea forms the basis of the hypothesis of self-perpetuating autoreactive B cells.
    • Autoreactive B cells in spontaneous autoimmunity are seen as surviving because of subversion both of the T cell help pathway and of the feedback signal through the B cell receptor.
    • In this process T-cells are stimulated to grow and can signal B-cells to produce antibodies.

  • Tests That Differentiate Between T Cells and B cells

    • Methods used to differentiate T cells and B cells include staining cell surface receptors and functional assays like the T lymphocyte cytotoxicity assay.
    • B-cells are also white blood cells and are a vital part of the humoral immunity branch of the adaptive immune system.
    • T-lymphocytes can be distinguished from other lymphocytes like B cells and natural killer cells (NK cells) by the presence of a T cell receptor (TCR) on the cell surface.
    • Alternatively, B-cells can be distinguished from other lymphocytes like T cells and natural killer cells (NK cells) by the presence of a protein on the B-cell's outer surface called a B-cell receptor (BCR).
    • The expression of different markers allows the separation/differentiation of T and B cells.

  • Isotype Class Switching

    • The antibody isotype of a B cell changes during cell development and activation.
    • Immature B cells, which have never been exposed to an antigen, are known as naïve B cells and express only the IgM isotype in a cell surface bound form.
    • B cells begin to express both IgM and IgD when they reach maturity; the co-expression of both of these immunoglobulin isotypes renders the B cell 'mature' and ready to respond to an antigen.
    • B cell activation follows engagement of the cell-bound antibody molecule with an antigen, causing the cell to divide and differentiate into an antibody-producing cell, called a plasma cell.
    • This allows different daughter cells from the same activated B cell to produce antibodies of different isotypes or subtypes (e.g.

  • Adaptive Immunity and the Immunoglobulin Superfamily

    • Immunoglobulins are produced in a membrane-bound form by B lymphocytes.
    • These membrane molecules function as B cell receptors for antigens.
    • The interaction of antigens with membrane antibodies on naive B cells initiates B cell activation .
    • These activated B cells produce a soluble form of immunoglobulin that triggers effector mechanisms to eliminate antigens.
    • When a B cell encounters its triggering antigen, it gives rise to many large cells known as plasma cells.

  • Development of the Dual Lymphocyte System

    • B cells and T cells are the major types of lymphocytes.
    • Mammalian stem cells differentiate into several kinds of blood cell within the bone marrow.
    • B cells mature into B lymphocytes in the bone marrow, while T cells migrate to, and mature in, a distinct organ called the thymus.
    • B and T cells) differentiate further after exposure to an antigen; they form effector and memory lymphocytes.
    • Effector lymphocytes function to eliminate the antigen, either by releasing antibodies (in the case of B cells), cytotoxic granules (cytotoxic T cells) or by signaling to other cells of the immune system (helper T cells).

  • Cells and Organs of the Immune System

    • The thymus "educates" T cells and provides an inductive environment for the development of T cells from hematopoietic progenitor cells.
    • Lymph nodes are garrisons of B, T and other immune cells.
    • B cells and T cells are the major types of lymphocytes and are derived from hematopoietic stem cells in the bone marrow.
    • In contrast, the B cell antigen-specific receptor is an antibody molecule on the B cell surface, which recognizes whole pathogens without any need for antigen processing.
    • Each lineage of B cell expresses a different antibody, so the complete set of B cell antigen receptors represent all the antibodies that the body can manufacture.

  • Classes of T Cells

    • T cells play a central role in cell-mediated immune response through the use of the surface T cell receptor to recognize peptide antigens.
    • T cells do not produce antibody molecules.
    • Effector cells include helper T cells, and cytolytic or cytotoxic T cells.
    • In response to antigenic stimulation, helper T cells (characterized by the expression of CD4 marker on their surface) secrete proteins called cytokines, whose function is to stimulate the proliferation and differentiation of the T cells themselves, as well as other cells, including B cells, macrophages, and other leukocytes.
    • Another class of T cells called regulatory T cells function to inhibit immune response and resolve inflammation.

  • MreB and Determinants of Cell Morphology

    • Prokaryotes carrying the mreB gene can also be helical in shape.
    • However, this model has been brought into question by three recent publications showing that filaments cannot be seen by electron cryotomography and that GFP-MreB can be seen as patches moving around the cell circumference.
    • Recent research shows that peptidoglycan precursors are inserted into cell wall following helical pattern which is dependent on MreB, and it's reported that MreB also promote the GT activity of PBPs.
    • MreB- RodZ complexes act as a major stabilizing factor in bacterial cell wall and ensure the insertion of new peptidoglycan in a spiral like fashion into the cell wall.
    • Procaryotic MreB in cartoon representation.

  • Natural Killer Cells

    • Natural killer cells (or NK cells) are a type of cytotoxic lymphocyte critical to the innate immune system.
    • NK cells are defined as large granular lymphocytes (LGL) and constitute the third kind of cell differentiated from the common lymphoid progenitor generating B and T lymphocytes.
    • Often NKT cell activity promotes NK cell activity by secreting IFNγ.
    • In contrast to NKT cells, NK cells do not express T-cell antigen receptors (TCR) or Pan T marker CD3 or surface immunoglobulins (Ig) B cell receptors, but they usually express the surface markers CD16 (FcγRIII) and CD56 in humans, NK1.1 or NK1.2 in C57BL/6 mice.
    • Functions of NK cells include: Cytolytic Granule Mediated Cell Apoptosis; Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC); Cytokine induced NK and CTL activation; Missing 'self' hypothesis; Tumor cell surveillance; NK cell function in adaptive response; NK cell function in pregnancy; and NK cell evasion by tumor cells .