Lymphocyte B Cell In The Immune System Biology Essay

Lymphocyte B Cell In The Immune System Biology EssayB cellular phone is a type of lymphocyte that is the seat for the bodys humoral immune system it is produced from the stem cell in the bone marrow (Darling, 2010). On its labor a self renewing hematopoietic stem cells produces lymphoid and myeloid progenitor.Looking mainly at lymphoid progenitor, it gives rise to B cell progenitor, T cell progenitor and Natural Killer cells (Kuby et al. 2007, p.25). lymphoid progenitor produces progenitor B cells it is the earliest identifiable cell thats committed to the development in the B cell linage. The cells moves and rearrange their Ig heavy chain elementtic segments to sterilise a functional IgH gene that are expressed as pre B cell receptors.The B cell receptor is a membrane bound antibody molecule. From the pre B cell receptor, some of the cells stays in the bone marrow and some moves into supplemental lymphoid organs and there they reproduce, also in the sary lymphoid organs the cells undergo antigen underage maturation. On the topic of B cell progenitor, it produces B cell and these B cells further undergo dickens phases of maturation an antigen independent phase and an antigen dependent phase (Kempert, 2010).During the development, each B cell is genetically programmed or a process known as gene translocation, to express a unique B cell receptor. The molecules of that B cell receptor are place on its surface where it batch react with epitopes of an antigen (Kaiser, 2010)Epitopes are antigenic determinants recognized and bound with B cell receptors and they are located on the surface of the antigen (Austin, 2010). at that place are known to be two main classes of B cell epitopes, one is Linear or continuous, the surface that are interacted with the antibody are located next to each other sequentially on the protein. The second one is assembled or discontinuous the components are located on disparate parts of the protein which are brought conformati onally coterminous to each other through side chain interactions (ProImmune, 2010).Produced B cells contain two types of B lymphocytes, blood plasma cells and memory cells which express CD19, CD20 and CD21 on these cells (Kempert, 2010). Plasma cells are a type of white blood cell that produces antibodies. Once produced, B cells mainly stay within the bone marrow and wait until an antigen invades the body. The antigens fetter to the B cell and stimulate it to form plasma cells.Plasma cells are known to have characteristic coming into court nuclei cytoplasm that contains dense rough endoplasmic reticulum and which is the site where antibodies are combined and also a typical perinuclear Golgi complexes where the antibody molecules are converted to their final forms and ready for secretion (Abbas et al. 2009, p. 22).Memory cells are produced by antigen stimulation of nave B cells, they have proteins that are expressed on their surface that distinguish them from B cells and Plasma c ells and they can survive in a functionally state for many years after the antigen has been eliminated and also they are known as B cell sub types that are formed after an initial transmission system (Abbas et al. 2009, p. 22).FunctionThe major function of B cell is the secretion of antibodies. When an antigen has invades the body and has been encountered by the immune system, they bind to B cell and a number of certain B lymphocyte are thence excited and undergo cell division to produce plasma cell and memory cells which is known as clonal expansion.Clonal expansion is a process that when a nave B cell encounter a pathogens antigen. As the antigen floats through the blood system it gets attaches and binds to the nave B cells. This trigger clonal expansion and the B cells multiples (Kuby et al. 2007, p.17).The B cell receptors are the ones responsible to bind to the antigens, the bounded antigen is then engulfed into the B cell by the receptor mediated endocytosis. The antigen are digested and broken down into small fragments and displayed on the cell surface thats academic term inside a class II Histocompatibility molecule.With the help of Helper T cells that binds with B cells, the B cells then secretes lymphokines that stimulates the B cells to go through a cell cycle that develops and turn the B cells from being B cell receptors to being a plasma cell that secrete antibodies(Kimball, 2010).The plasma cell each produces a particular antibody thats specifically attached to a specific antigen and these plasma cells are secreted into the blood system. As a specific antibody has attached to a specific antigen, the antibodies produce a humoral response and inactivate the pathogen, and make it easier to removal from the body (Anglin, 2010). Once this process has occurred meaning once the body defense has encountered and destroyed the pathogens antigen, the body remember this pathogens antigen and this remembering process is referred to as Memory cell.Memory ce lls are produced by stimulated B cells, they are the form of basis for long term immunity and responsible for secondary response. As presently as an infection that was previously destroyed by the humoral immune system returns the memory cells that has tarry dormant produce a quick response and the infection is removed as quickly and efficaciously leaving the patient immune (Martin, 2010).