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B cells undergo two types of selection while developing in the bone marrow to ensure proper development, both involving B cell receptors (BCR) on the surface of the cell. Positive selection occurs through antigen-independent signalling involving both the pre-BCR and the BCR.
This figure depicts the process of B cell selection in the bone marrow. Immature B cells in the bone marrow undergo negative selection when they bind self peptides. [2] Properly functioning B cell receptors recognize non-self antigen, or pathogen-associated molecular proteins . [1] Main outcomes of autoreactivity of BCRs [1] [2]
GC B cells that are best able to present antigen to T follicular helper cells and produce the strongest B cell receptor signal are positively selected in the light zone of the germinal center. [4] Therefore, positive selection of GC B cells in the light zone results in B cells that express antibodies with high affinity for the antigen. [3]
The follicular dendritic cells (FDCs) of the germinal centers present antigen to the B cells, and the B cell progeny with the highest affinities for antigen, having gained a competitive advantage, are favored for positive selection leading to their survival. Positive selection is based on steady cross-talk between T FH cells and their cognate ...
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]
The process of immunological B-cell maturation involves transformation from an undifferentiated B cell to one that secretes antibodies with particular specificity. [1] This differentiation and activation of the B cell occurs most rapidly after exposure to antigen by antigen-presenting cells in the reticuloendothelial system, and under modulation by T cells, and is closely intertwined with ...
Some B cells will undergo a process known as affinity maturation. [9] This process favors, by selection for the ability to bind antigen with higher affinity, the activation and growth of B cell clones able to secrete antibodies of higher affinity for the antigen. [10]
Somatic hypermutation (or SHM) is a cellular mechanism by which the immune system adapts to the new foreign elements that confront it (e.g. microbes).A major component of the process of affinity maturation, SHM diversifies B cell receptors used to recognize foreign elements and allows the immune system to adapt its response to new threats during the lifetime of an organism. [1]