The immune system protects the body from illness and infection. One significant component is a protein called B-cell Activating Factor, often referred to as BAFF. BAFF plays a role in maintaining the body’s defenses. Understanding BAFF clarifies how these protective mechanisms operate.
Understanding B-cell Activating Factor
B-cell Activating Factor, known scientifically as TNFSF13B, is a protein and a signaling molecule in the immune system. It belongs to the tumor necrosis factor (TNF) ligand family. This protein is produced by various immune cells, including monocytes, macrophages, dendritic cells, T-lymphocytes, and cells in bone marrow, spleen, and lymph nodes.
BAFF circulates in the bloodstream and is present in lymph nodes throughout the body. It functions as a cytokine, a substance influencing the activity of other immune cells. BAFF interacts with specific receptors on the surface of immune cells, facilitating communication and regulating their behavior.
How BAFF Influences Immunity
BAFF primarily influences B cells, white blood cells that produce antibodies. BAFF plays a direct role in the development, survival, and activation of these B cells. Without adequate BAFF, B cells may not mature properly or survive long enough to perform their functions.
BAFF binds to several receptors on B cells, including BAFF-R, TACI, and BCMA, with BAFF-R being particularly important for B cell survival. This interaction ensures a healthy population of B cells, enabling them to produce antibodies that identify and neutralize foreign invaders like bacteria and viruses. BAFF also activates specific signaling pathways within B cells, such as the noncanonical NF-κB pathway, supporting their maturation and effective response to threats.
BAFF’s Link to Health Conditions
When BAFF levels are not properly regulated, they can contribute to various health issues. Both excessively high or unusually low levels of this protein can disrupt immune balance. Elevated BAFF levels are particularly associated with autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues.
Conditions such as Systemic Lupus Erythematosus (SLE), rheumatoid arthritis, Sjögren’s syndrome, and IgA nephropathy often show increased BAFF concentrations in the blood. In these diseases, high BAFF levels can lead to overactive B cells that produce autoantibodies, which target and damage healthy body cells. Researchers are exploring BAFF as a target for therapeutic interventions, with inhibitors like belimumab showing promise in clinical trials for conditions such as SLE by normalizing B cell activity.