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B cells, unlike the other two classes of lymphocytes, T cells and natural killer cells, express B cell receptors (BCRs) on their cell membrane. [1] BCRs allow the B cell to bind to a foreign antigen, against which it will initiate an antibody response. [1] B cell receptors are extremely specific, with all BCRs on a B cell recognizing the same ...
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]
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]
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 ...
Unlike their MZ counterpart, FO B cells freely recirculate, comprising >95% of the B cells in peripheral lymph nodes. The BCR repertoire of the follicular B cell compartment also appears under positive selection pressures during final maturation in the spleen. However, diversity is substantially broader than B1 B and MZ B cell compartments.
(2) Isolation of B cells from the spleen (3) Cultivation of myeloma cells (4) Fusion of myeloma and B cells (5) Separation of cell lines (6) Screening of suitable cell lines (7) in vitro (a) or in vivo (b) multiplication (8) Excised spleen processed for antibody extraction Hybridoma cells grown in tissue culture. The image shows a single clone ...
Cells that survive positive selection, but bind strongly to self-antigens are negatively selected also by active induction of apoptosis. This negative selection is known as clonal deletion, one of the mechanisms for B cell tolerance. Approximately 99 percent of pre-B cells within the thymus are negatively selected. Only approximately 1 percent ...
In order for lymphocytes such as T cells to become immunocompetent, which refers to the ability of lymphocyte cell receptors to recognize MHC molecules, they must undergo positive selection. [ 1 ] Adaptive immunocompetence is regulated by growth hormone (GH), prolactin (PRL), and vasopressin (VP) – hormones secreted by the pituitary gland.