lymphocyte

(noun)

A type of white blood cell or leukocyte that is divided into two principal groups and a null group: B-lymphocytes, which produce antibodies in the humoral immune response, T-lymphocytes, which participate in the cell-mediated immune response, and the null group, which contains natural killer cells, cytotoxic cells that participate in the innate immune response.

Related Terms

Examples of lymphocyte in the following topics:

  • Development of the Dual Lymphocyte System

    • B cells and T cells are the major types of lymphocytes.
    • During this process, all lymphocytes originate from a common lymphoid progenitor before differentiating into their distinct lymphocyte types.
    • The formation of lymphocytes is known as lymphopoiesis.
    • The lymphocytes involved in adaptive immunity (i.e.
    • All lymphocytes originate during this process from a common lymphoid progenitor before differentiating into their distinct lymphocyte types.

  • Clonal Selection and Tolerance

    • It was hypothesized that it is the age of the lymphocyte that defines whether an antigen that is encountered will induce tolerance, with immature lymphocytes being tolerance sensitive.
    • clonal selection of the B and T lymphocytes:1.
    • Immature lymphocytes with various receptors 3.
    • Mature, inactive lymphocytes 5.
    • Cloned activated lymphocytes.

  • Tests That Differentiate Between T Cells and B cells

    • T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes.
    • 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.
    • T-lymphocytes express CD3, CD4, CD8, or CD25 markers.
    • B-lymphocytes express CD19 marker.
    • A scanning electron microscope (SEM) image of a single human lymphocyte.

  • Clonal Selection of Antibody-Producing Cells

    • Each lymphocyte bears a single type of receptor with a unique specificity (by V(D)J recombination).
    • Those lymphocytes bearing receptors for self molecules will be deleted at an early stage.
    • B cells that have not been activated by antigen are known as naive lymphocytes; those that have met their antigen, become activated, and have differentiated further into fully functional lymphocytes are known as effector B lymphocytes.
    • Clonal selection of lymphocytes: 1) A hematopoietic stem cell undergoes differentiation and genetic rearrangement to produce 2) immature lymphocytes with many different antigen receptors.
    • Those that bind to 3) antigens from the body's own tissues are destroyed, while the rest mature into 4) inactive lymphocytes.

  • Adaptive Immunity and the Immunoglobulin Superfamily

    • The components of adaptive immunity are lymphocytes and their products.
    • Protective immunity against a microbe may be induced by the host's response to the microbe or by the transfer of antibodies or lymphocytes specific for the microbe.
    • Immunoglobulins are produced in a membrane-bound form by B lymphocytes.
    • Members of the IgSF include cell surface antigen receptors, co-receptors, and co-stimulatory molecules of the immune system, molecules involved in antigen presentation to lymphocytes, cell adhesion molecules, certain cytokine receptors, and intracellular muscle proteins.

  • Primary Immunodeficiency Diseases

    • The basic tests performed when an immunodeficiency is suspected should include a full blood count ( including accurate lymphocyte and granulocyte counts) and immunoglobulin levels.
    • Quantification of the different types of mononuclear cells in the blood (lymphocytes and monocytes): different groups of T lymphocytes (dependent on their cell surface markers, e.g.
    • CD4+, CD8+, CD3+, TCRα and TCRγ); groups of B lymphocytes (CD19, CD20, CD21 and Immunoglobulin); natural killer cells and monocytes (CD15+); as well as activation markers (HLA-DR, CD25, CD80 (B cells)
    • In genetic immunodeficiency disorders, both T lymphocytes and often B lymphocytes—regulators of adaptive immunity—are dysfunctional or decreased in number.
    • Several rare conditions are due to defects in the innate immune system, which is a basic line of defense independent of the more advanced lymphocyte-related systems.

  • Cardiovascular and Lymphatic System Defenses

    • Lymphoid tissues contain lymphocytes, but they also contain other types of cells for support.
    • As well as filtering the lymph, lymph nodes produce the white cells known as lymphocytes.
    • Lymphocytes are also produced by the thymus, spleen and bone marrow.
    • There are two kinds of lymphocyte.
    • In the lymph nodes, the macrophages and dendritic cells phagocytose the antigens, process them, and present the antigens to lymphocytes, which can then start producing antibodies or serve as memory cells.

  • Natural Killer Cells

    • Natural killer cells (or NK cells) are a type of cytotoxic lymphocyte critical to the innate immune system.
    • 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.

  • Cells and Organs of the Immune System

    • Bone marrow and thymus constitute the primary lymphoid tissues involved in the production and early selection of lymphocytes.
    • They are packed tightly with the white blood cells, called lymphocytes and macrophages.
    • The cells of the adaptive immune system are special types of leukocytes, called lymphocytes .
    • B cells and T cells are the major types of lymphocytes and are derived from hematopoietic stem cells in the bone marrow.
    • Red blood cells, several white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shaped platelets.

  • Classes of T Cells

    • Cellular immunity is mediated by T lymphocytes, also called T cells.
    • This activation results in the expansion of the antigen-specific lymphocyte pool and the differentiation of these cells into effector and memory cells.