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B cells produce antibody molecules which may be either secreted or inserted into the plasma membrane where they serve as a part of B-cell receptors. [2] When a naïve or memory B cell is activated by an antigen, it proliferates and differentiates into an antibody-secreting effector cell, known as a plasmablast or plasma cell. [2]
Memory B cells circulate in the blood stream in a quiescent state, sometimes for decades. [1] Their function is to memorize the characteristics of the antigen that activated their parent B cell during initial infection such that if the memory B cell later encounters the same antigen, it triggers an accelerated and robust secondary immune response.
Germinal centers or germinal centres (GCs) are transiently formed structures within B cell zone (follicles) in secondary lymphoid organs – lymph nodes, ileal Peyer's patches, and the spleen [1] – where mature B cells are activated, proliferate, differentiate, and mutate their antibody genes (through somatic hypermutation aimed at achieving higher affinity) during a normal immune response ...
Upon stimulation by a T cell, which usually occurs in germinal centers of secondary lymphoid organs such as the spleen and lymph nodes, the activated B cell begins to differentiate into more specialized cells. Germinal center B cells may differentiate into memory B cells or plasma cells. Most of these B cells will become plasmablasts (or ...
A B-cell receptor includes both CD79 and the immunoglobulin. The plasma membrane of a B cell is indicated by the green phospholipids. The B- cell receptor extends both outside the cell (above the plasma membrane) and inside the cell (below the membrane). The B-cell receptor (BCR) is a transmembrane protein on the surface of a B cell.
Mechanism of class-switch recombination that allows isotype switching in activated B cells. Immunoglobulin class switching, also known as isotype switching, isotypic commutation or class-switch recombination (CSR), is a biological mechanism that changes a B cell's production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG. [1]
In immunology, a naive B cell is a B cell that has not been exposed to an antigen. These are located in the tonsils , spleen , and primary lymphoid follicles in lymph nodes . Once exposed to an antigen , the naive B cell either becomes a memory B cell or a plasma cell that secretes antibodies specific to the antigen that was originally bound.
The latter case induces recognition by antigen-specific Th2 cells or Tfh cells, leading to activation of the B cell through binding of TCR to the MHC-antigen complex. It is followed by synthesis and presentation of CD40L (CD154) on the Th2 cell, which binds to CD40 on the B cell, thus the Th2 cell can co-stimulate the B cell. [11]