BAFF receptor polymorphisms and deficiency in humans.

The BAFF-receptor (BAFFR) is a member of the TNF-receptor family. It is expressed only by B cells and binds BAFF as single ligand, which activates key signaling pathways regulating essential cellular functions, including survival, protein synthesis, and metabolic fitness. In humans, BAFFR deficiency interrupts B cell development at the transition from immature to mature B cells and causes B lymphopenia, hypogammaglobulinemia, and impaired humoral immune responses. Polymorphisms in TNFRSF13C gene affecting BAFFR oligomerization and signaling have been described in patients with immunodeficiency, autoimmunity and B cell lymphomas. Despite a uniform expression pattern of BAFFR in peripheral mature B cells, depletion of BAFF with neutralizing antibodies in patients with systemic lupus erythematosus does not affect the survival of switched memory B cells. These findings imply a distinct dependency of mature B cell subsets on BAFF/BAFFR interaction and highlight the contribution of BAFFR-derived signals in peripheral B cell development and homeostasis.
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