plasma cell

(noun)

a form of lymphocyte that produces antibodies when reacted with a specific antigen; a plasmacyte

Related Terms

Examples of plasma cell in the following topics:

  • Adaptive Immunity and the Immunoglobulin Superfamily

    • 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 .
    • When a B cell encounters its triggering antigen, it gives rise to many large cells known as plasma cells.
    • Every plasma cell is essentially a factory for producing an antibody.
    • Each of the plasma cells manufactures millions of identical antibody molecules and pours them into the bloodstream.

  • Injuring the Plasma Membrane

    • The plasma membrane or cell membrane is a biological membrane that separates the interior of all cells from the outside environment.
    • The plasma membrane is selectively permeable to ions and organic molecules.
    • Plasma membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity, and cell signaling.
    • The plasma membrane also plays a role in anchoring the cytoskeleton to provide shape to the cell and in attaching to the extracellular matrix and other cells to help group cells together to form tissues .
    • Diagram of a typical gram-negative bacterium, with the thin cell wall sandwiched between the red outer membrane and the thin green plasma membrane.

  • 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 .
    • In the wake of the first (primary response) infection involving a particular antigen, the responding naïve cells (ones which have never been exposed to the antigen) proliferate to produce a colony of cells.
    • 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.
    • The fact that all the cells of a single clone elaborate one (and only one) paratope, and that the memory cells survive for long periods, is what imparts a memory to the immune response.

  • Gram-Negative Outer Membrane

    • The Gram-negative cell wall is composed of an outer membrane, a peptidoglygan layer, and a periplasm.
    • In the Gram-negative Bacteria the cell wall is composed of a single layer of peptidoglycan surrounded by a membranous structure called the outer membrane.
    • It contains structures that help bacteria adhere to animal cells and cause disease.
    • Sandwiched between the outer membrane and the plasma membrane, a concentrated gel-like matrix (the periplasm) is found in the periplasmic space.
    • Together, the plasma membrane and the cell wall (outer membrane, peptidoglycan layer, and periplasm) constitute the gram-negative envelope.

  • Replicative Cycle of HIV

    • HIV can infect dendritic cells (DCs).
    • HIV enters macrophages and T cells by the adsorption of glycoproteins on its surface to receptors on the target cell.
    • The final step of the viral cycle, assembly of new HIV-1 virions, begins at the plasma membrane of the host cell.
    • These are transported to the plasma membrane of the host cell where gp41 anchors gp120 to the membrane of the infected cell.
    • The Gag (p55) and Gag-Pol (p160) polyproteins also associate with the inner surface of the plasma membrane along with the HIV genomic RNA as the forming virion begins to bud from the host cell.

  • Sodium Pumps as an Alternative to Proton Pumps

    • Na+/K+-ATPase (Sodium-potassium adenosine triphosphatase, also known as Na+/K+ pump, sodium-potassium pump, or sodium pump) is an antiporter enzyme (EC 3.6.3.9) (an electrogenic transmembrane ATPase) located in the plasma membrane of all animal cells.
    • The mechanism responsible for this is the sodium-potassium pump, which moves these two ions in opposite directions across the plasma membrane.
    • This was investigated by following the passage of radioactively labeled ions across the plasma membrane of certain cells.
    • It marked an important step in our understanding of how ions get into and out of cells, and has a particular significance for excitable cells like nervous cells, which depend on this pump for responding to stimuli and transmitting impulses.
    • In most animal cells, the Na+/K+-ATPase is responsible for about 1/5 of the cell's energy expenditure.

  • Inhibiting Cell Wall Synthesis

    • Antibiotics commonly target bacterial cell wall formation (of which peptidoglycan is an important component) because animal cells do not have cell walls.
    • Diagram depicting the failure of bacterial cell division in the presence of a cell wall synthesis inhibitor (e.g. penicillin, vancomycin).1- Penicillin (or other cell wall synthesis inhibitor) is added to the growth medium with a dividing bacterium.2- The cell begins to grow, but is unable to synthesize new cell wall to accommodate the expanding cell.3- As cellular growth continues, cytoplasm covered by plasma membrane begins to squeeze out through the gap(s) in the cell wall.4- Cell wall integrity is further violated.
    • The cell continues to increase in size, but is unable to "pinch off" the extra cytoplasmic material into two daughter cells because the formation of a division furrow depends on the ability to synthesize new cell wall.5- The cell wall is shed entirely, forming a spheroplast, which is extremely vulnerable relative to the original cell.
    • The loss of the cell wall also causes the cell to lose control over its shape, so even if the original bacterium were rod-shaped, the sphereoplast is generally spherical.
    • Finally, the fact that the cell has now doubled much of its genetic and metabolic material further disrupts homeostasis, which usually leads to the cell's death.

  • Viral Exit

    • Viruses can be released from the host cell by lysis, a process that kills the cell by bursting its membrane and cell wall if present.
    • During this process the virus acquires its envelope, which is a modified piece of the host's plasma or other, internal membrane.
    • The viral envelope is the typical lipid bilayer, derived from the host cell itself and sources usually come from the nuclear membrane, endoplasmic reticulum, Golgi apparatus/body, and plasma membrane.
    • This process will slowly use up the cell membrane and eventually lead to the demise of the cell.
    • Viral budding uses the host's cell membrane eventually causing cell death.

  • General Features of Virus Replication

    • The infection of plant and fungal cells is different from that of animal cells.
    • Plants have a rigid cell wall made of cellulose, and fungi one of chitin, so most viruses can get inside these cells only after trauma to the cell wall.
    • Bacteria, like plants, have strong cell walls that a virus must breach to infect the cell.
    • Viruses can be released from the host cell by lysis, a process that kills the cell by bursting its membrane and cell wall if present.
    • During this process the virus acquires its envelope, which is a modified piece of the host's plasma or other internal membrane.

  • Gram-Positive Cell Envelope

    • Gram-positive bacteria have cell envelopes made of a thick layer of peptidoglycans.
    • It is based on the chemical and physical properties of their cell walls.
    • In Gram-positive bacteria, the cell wall is thick (15-80 nanometers), and consists of several layers of peptidoglycan.
    • The teichoic acid polymers are occasionally anchored to the plasma membrane (called lipoteichoic acid, LTA), and apparently directed outward at right angles to the layers of peptidoglycan.
    • Another theory is that teichoic acids are in some way involved in the regulation and assembly of muramic acid sub-units on the outside of the plasma membrane.