Lymphoid Cell Line

The lymphoid cell line consists of those blood cells that begin in the bone marrow in a process called hematopoiesis, and descend from a common lymphoid stem cell.

Hematopoiesis

The production of all "blood cells" begins in the bone marrow in a process known as hematopoiesis.  In this process, all types of blood cells originate from a hematopoietic stem cell.  This original cell, also called a multipotent stem cell, can be likened to Adam in the bible, as the "father cell" from which all other blood cells are spawned.

  These cells are also called pluripotent stems cells, meaning that they have the potential to become many different types of cells.

The first specialization of cells occurs when this pluripotent cell follows one of two development pathways called cell lines.  The pluripotent stem cell can differentiate into either the myeloid cell line or the lymphoid cell line.

Lymphoid Stem Cell - Lymphoblast

The lymphoid cell line begins with a lymphoid stem cell, also known as a lymphoblast or lymphoid progenitor cell.  This is a major fork in the road as all cells in this line begin with a lymphoid progenitor cell, whereas all cells in the myeloid line (such as neutrophils, macrophages, and red blood cells) begin with a myeloid progenitor cell.

Lymphoid Cell Line Cells

The lymphoid progenitor cell (lymphoblast) can subsequently differentiate further into more specialized into cells which include:

  • T lymphocytes - T lymphocytes, or "T cells" are cells in the immune system that find, kill, and organize a war against foreign matter such as bacteria, viruses, and cancer cells.
  • Natural killer cell - Natural killer cells are aggressive cells of the immune system that act to eliminate cancer cells and virus-infected cells.

    Lymphoid Cell Line and Immunity

    Lymphoid lineage cells make up about 15% of the cells in healthy bone marrow.  Hematopoietic stem cells are continuously differentiating into lymphoid progenitor cells which in turn continually differentiate into the mature cells which make up the lymphoid cell line.  It's estimated that the bone marrow turns out at least 100 million white blood cells per hour.

    Lymphoid Malignancies

    Cancers involving cells in the lymphoid line include:

    • Non-Hodgkin lymphomas - Non-Hodgkin lymphomas consist of a diverse groupof lymphomas that can involve either B cells or T cells.  These cancers are ranked in the top 10 causes of cancer-related deaths for both men and for women.
    • Hodgkin lymphomas - Hodgkin lymphomas are also fairly common cancers, and are currently the most common cancer diagnosed in young adults between the age of 15 and 25.
    • Acute lymphocytic leukemia (ALL) - Acute lymphocytic leukemia is a cancer that involves lymphoblasts - the cells that go on to become B cells, T cells, and natural killer cells.  It is most common in children under the age of 10 but can occur at any age.
    • Chronic lymphocytic leukemia  (CLL) - Chronic lymphocytic leukemia is a cancer which in the United States affects mostly B lymphocytes.  T cell CLL, in contrast, is more common in parts of Japan.

    Sources:

    Liu, A., Wang, Y., Ding, Y. et al. Cutting Edge: Hematopoietic Stem Cell Expansion and Common Lymphoid Progenitor Depletion Require Hematopoietic-Derived, Cell-Autonomous TLR4 in a Model of Chronic Endotoxin. Journal of Immunology. 2015. 196(6):2524-8.

    Sieff, C. Overview of hematopoiesis and stem cell function. UpToDate. Updated 05/26/15. http://www.uptodate.com/contents/overview-of-hematopoiesis-and-stem-cell-function

    Liang, H., and J. Zuniga-Pflucker. Hematopoiesis: from start to immune reconstitution potential. Stem Cell Research & Therapy. 2015. DOI: 10.1186/s13287-015-0051-z

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