Researchers have identified a molecule that reduces production of antibodies by a specialized set of immune cells reports a paper online in Nature Immunology.
Lars Nitschke and colleagues discovered Siglec-G (sialic acid binding immunoglobulin-like lectin), is highly expressed in a subset of antibody-producing cells called B1 B cells. These cells arise early in life and produce weak antibodies, often called 'natural' antibodies that can recognize many different antigens including 'self-tissues'. Siglec-G acts to desensitize these B1 cells by damping down signalling pathways within these cells when triggered by antigen contact. Mice lacking Siglec-G have higher numbers of B1 cells and substantially more 'natural' antibodies in their blood, including autoantibodies known as rheumatoid factors. Thus, Siglec-G acts as a brake to reduce the potential for excessive antibody production.
The findings point to a possible risk factor for developing autoimmunity disease should mutations arise in the gene encoding Siglec-G that alter its function.
Lars Nitschke (University of Erlangen, Germany)
Abstract available online.
(C) Nature Immunology press release.
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