Mechanism of antigen-driven selection in germinal centres
Article Abstract:
The body's natural defense system, the immune system, consists of specialized cells and factors that recognize, inactivate and destroy foreign invading substances called antigens. Most B lymphocytes, a type of immune cell, die after being produced in the bone marrow, but some migrate to secondary lymphoid tissue such as the tonsils. In the presence of an antigen, these B lymphocytes transform into B cells, which produce proteins called antibodies that specifically recognize, bind and inactivate the antigen. The structure of an antibody consists of a constant region, which binds certain factors involved in enhancing the immune response, and the variable region, which binds antigen. Recent studies indicate that the affinity or ability of an antibody to bind an antigen is due to rearrangement of genes in the B lymphocytes that code for the variable region of the antibody. It was also found that centrocytes, a type of B cell in lymphoid tissue such as tonsils, disintegrate within a few hours if they are not activated by an antigen. Centrocytes that do not bind antigen are eliminated or are selected against, whereas those that bind antigen survive or are selected for, and help mediate the immune response. It is thought that the defects in the selection process of these B cell-type centrocytes might be involved in the formation of lymphomas, tumors of the lymphoid tissue. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1989
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Antigen-induced B-cell death and elimination during germinal-centre immune responses
Article Abstract:
A new method was developed for visualizing the outcome of antigen-specific B cells during germinal center (GC) reactions by seeding a current immune response with lysozyme-specific B cells taken from transgenic animals with immunoglobulin genes. Soluble antigen, when administered at the GC's response peak, quickly eliminates lysozyme-specific GC B cells in two apoptosis waves. One wave is within the GC, while the other is in cells that have transferred to T cell-rich lymphoid zones. Results show censoring measures that could prevent the autoantibodies' affinity maturation toward systemic autoantigens.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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Soluble antigen can cause enhanced apoptosis of germinal-centre B cells
Article Abstract:
A research study proves that antigen-specific, high-affinity, germinal-center B cells quickly die via in situ apoptosis when soluble antigens are encountered. The effect appears to act directly on the B cells instead of acting first on helper T cells. In addition, the apoptosis is observed only in germinal-center cells and is only incompletely hindered by the proto-oncogene bcl-2's constitutive expression. This could imply the clonal deletion of self-reactive B cells in germinal centers.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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