Plasma cells (also called plasma B cells or plasmocytes) are cells of the immune system that secrete large amounts of antibodies. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily They differentiate from B cells upon stimulation by CD4+ lymphocytes. B cells are Lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by The B cell acts as an antigen presenting cell (APC), consuming an offending pathogen. See also Antigen presentation An antigen-presenting cell ( APC) or accessory cell is a cell that displays foreign Antigen complexed A pathogen (from Greek πάθος pathos "suffering passion" and γἰγνομαι (γεν- gignomai (gen- "I give birth to" infectious That pathogen gets taken up by the B cell by receptor mediated endocytosis, and broken down within these endosomes after fusion with lysosomes releasing proteolytic enzymes onto the pathogen. Lysosomes are Organelles that contain Digestive enzymes (acid Hydrolases. Once the enzymes break down the pathogen, pieces of the pathogen (which are now known as antigenic peptides) are loaded onto MHC II molecules, and presented on its extracellular surface. MHC ( Major histocompatibility complex) Class II molecules are found only on a few specialized cell types including Macrophages Dendritic cells and Once on the extracellular surface, the CD4+ T-helper lymphocyte will bind to the MHC II/Antigen molecule and cause activation of the B cell, which includes differentiation into a plasma cell, and subsequent generation of antibody against the consumed pathogen.
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Overview
After dividing for around five days, mature B cells differentiate into either plasma B cells or memory B cells. Memory B cells are a B cell sub-type that are formed following primary infection Plasma B cells originate in the bone marrow, then travel to the spleen or lymph nodes to secrete antibodies (approximately 10,000 per second). Bone marrow is the flexible tissue found in the hollow interior of Bones In adults marrow in large bones produces new Blood cells It constitutes 4% of The spleen is an organ found in all Vertebrate animals In humans the spleen is located in the abdomen of the body where it functions in the destruction of redundant Red A Lymph node ( lɪmf noʊd is an organ consisting of many types of cells and is a part of the Lymphatic system. During the initial stages of an immune response the lifespan of plasma cells is very short, typically only a few days to weeks. However, following the process of affinity maturation, plasma cells can survive for months to years and continue to secrete high levels of antibodies. Memory B cells tend to be longer-lived and can therefore respond quickly upon second exposure to an antigen.
The class of antibody that a plasma cell produces depends on signals, called cytokines, from other immune system cells, such as macrophages and T helper cells. Cytokines are a category of signalling Proteins and Glycoproteins that like Hormones and Neurotransmitters, are used extensively in cellular Macrophages ( Greek: "big eaters" from makros "large" + phagein "eat" ( Mø) are cells within the tissues that T helper cells (also known as effector T cells or Th cells) are a sub-group of Lymphocytes (a type of White blood cell or This process is called isotype-switching. For example, plasma cells will likely secrete IgG3 antibodies if they matured in the presence of the cytokine interferon-gamma. Immunoglobulin G ( IgG) is a Monomeric Immunoglobulin, built of two heavy chains γ and two light chains. Interferon-gamma ( IFN-γ) is a Dimerized soluble Cytokine that is the only member of the type II class of Interferons This interferon was originally Since B cell maturation also involves somatic hypermutation, these antibodies have a very high affinity for their antigen. Somatic hypermutation (or SHM is a mechanism inside cells that is part of the way the immune system adapts to the new foreign elements which confront it (for example
Microscopic anatomy
Plasma cells are large lymphocytes with a considerable nucleus-to-cytoplasm ratio and a characteristic appearance on light microscopy. In Cell biology, the nucleus (pl nuclei; from Latin la ''nucleus'' or la ''nuculeus'' "little nut" or kernel is a membrane-enclosed The cytoplasm is the contents of a cell that is enclosed within the Plasma membrane. Microscopy is the technical field of using microscopes to view samples or objects They have basophilic cytoplasm and an eccentric nucleus with heterochromatin in a characteristic cartwheel arrangement. Basophilic is a technical term used by histologists. It describes the microscopic appearance of cells and tissues as seen down the Microscope, Heterochromatin is a tightly packed form of DNA Its major characteristic is that transcription is limited Their cytoplasm also contains a pale zone that on electron microscopy contains an extensive Golgi apparatus and centrioles (EM picture). An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image The Golgi apparatus (also called the A Centriole is a barrel shaped Organelle found in most animal Eukaryotic cells though absent in Higher plants and Fungi. Abundant rough endoplasmic reticulum combined with a well-developed Golgi apparatus makes plasma cells well-suited for secreting immunoglobulins. The endoplasmic reticulum (Greek endo = "within" (prefix plásma = "formed entity" Latin reticulum = "little net" or ER, is an Organelle
Role in disease
Cancer of plasma cells is termed multiple myeloma. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled Multiple myeloma (also known as MM, myeloma, plasma cell myeloma, or as Kahler's disease after Otto Kahler) is a type of This condition is frequently identified because malignant plasma cells continue producing an antibody, which can be detected as a paraprotein. A paraprotein is an abnormal Protein in the Urine or Blood, most often associated with benign MGUS (monoclonal gammopathy of undetermined significance
Common variable immunodeficiency is thought to be due to a problem in the differentiation from lymphocytes to plasma cells. Common variable immunodeficiency (CVID is a group of 20-30 primary immunodeficiencies (PIDs which have a common set of symptoms (including Hypogammaglobulinemia) In Developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized Cell type. The result is a low serum antibody level and risk of infections.
External links
- Histology at BU 21001loa
- plasma+cell at eMedicine Dictionary
- c_18/12224615 at Dorland's Medical Dictionary
- Histology at wadsworth.org
Dictionary
plasma cell
-noun
- a form of lymphocyte that produces antibodies when reacted with a specific antigen; a plasmacyte
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