Cells in the immune system that help to kick off an immune response. Ordinarily, the immune system clears out damaged tissues and protects the body from invaders such as bacteria and viruses. However, in people with autoimmune conditions such as rheumatoid arthritis (RA) and systemic lupus erythematosus (lupus), the immune system attacks the body’s own healthy tissues. B cells are believed to play a major role in this autoimmune assault.
In RA, the target of the attack is often the tissue lining the joints (the synovium), which can lead to pain and swelling. Other organs may also be affected.
B cells are lymphocytes (a kind of white blood cell) that manufacture antibodies, proteins that normally recognize and neutralize or help to neutralize foreign substances and invaders in the body. Because of their role in autoimmune attacks, researchers have developed drugs that target them. Rituximab (brand name Rituxan) temporarily depletes B cells and has been shown to be useful in treating RA. Belimumab (Benlysta) inhibits a chemical in the body that stimulates B cells and was approved by the US Food and Drug Administration (FDA) in March of 2011 for treating lupus. Research into the role of B cells in autoimmune conditions–and as a target for treatment–continues.