BAFF

Acronym for "soluble human B lymphocyte stimulator protein". BAFF(BLyS) is a naturally occurring protein that is critical for the maturation, survival and function of B lymphocytes. BAFF is a member of the tumor necrosis factor superfamily (see Tumor necrosis factor-α below) and is present in a membrane-bound form and dissolved in its active form. BAFF is expressed on cells of the innate immune system, on neutrophil granulocytes, monocytes and macrophages; furthermore on dendritic cells and some T and B cells.

3 different receptors are currently detected on B cells:

BLys receptor 1-3, with BLyS receptor 3 (BR3, syn. BAFF3) being considered the most important. The BLyS3 receptor exerts a critical function in antibody production by inhibiting selection and apoptosis of autoreactive B cells.

In SLE patients (see below Lupus erythematosus, systemic), serum levels of BAFF have been shown to be elevated and correlate with double-stranded antibody levels. It is likely that in systemic lupus erythematosus and certain other autoimmune diseases, elevated BLyS levels contribute to the production of autoantibodies. Inhibition of BAFF by a monoclonal antibody(belimumab) resulted in an improvement of the clinical picture.

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