Where does antigen dependent development of B cells occur?
The antigen-dependent phase of B cell development involves activated B cell proliferation, antibody affinity maturation, and antibody class switching, all of which occurs in the germinal centers of secondary lymphoid tissues.
How are B cells activated by antigen?
B cells are activated when their B cell receptor (BCR) binds to either soluble or membrane bound antigen. This activates the BCR to form microclusters and trigger downstream signalling cascades.
What is dependent B cell activation?
T cell-dependent activation of B cells involves processing and presentation of protein antigens to helper T cells, activation of the B cells by cytokines secreted from activated TH2 cells, and plasma cells that produce different classes of antibodies as a result of class switching. Memory B cells are also produced.
How do B cells develop in bone marrow?
B cells are generated from hematopoietic stem cells (HSCs) in the liver during the fetal life, and in the bone marrow in the adult.
How are B cells activated by thymus dependent antigens?
B-cell activation by a thymus-dependent antigen comprises a sequence of events. An antigen crosslinks mIg, generating signal 1, which leads to increased expression of class II MHC and costimulatory B7. Antigen–mIg complexes are internalized by receptor-mediated endocytosis and degraded to peptides.
How do B cells develop and function?
B cells change their location with their stages of maturation, each location providing the microenvironment suitable for the B cell at that life stage. Stem cells produce lymphoid progenitors and pro-B cells in the marrow just under the bone. Developing B cells move toward the center of the marrow as they mature.
What is dependent antigen?
A thymus-dependent antigen is an immunogen that requires T cell cooperation with B cells to synthesize specific antibodies. Presentation of thymus-dependent antigen to T cells must be in the context of MHC class II molecules.
Do B cells require antigen presentation?
While B cells can interact with soluble antigens, it is now clear that the presentation of membrane-bound antigen plays a crucial role in B cell activation, and in particular during affinity-maturation, the process during which high-affinity B cells are selected.
How do B cells produce unique antigen receptors?
Each B cell clone makes antibody molecules with a unique antigen-binding site. Initially, during B cell development in the bone marrow, the antibody molecules are inserted into the plasma membrane, where they serve as receptors for antigen.