According to NIAID, "Lymphocytes bear the major responsibility for carrying out the activities of the immune system." The two major classes of lymphocytes are:
- B-cells (which are derived from bone marrow and develop into plasma cells that are the source of antibodies)
- T-cells (which are processed in the thymus and secrete lymphokines)
Antibodies can attach to a specific site on an antigen in order to block it or render it harmless. Any substance capable of triggering an immune response is called an antigen."
NIAID reports, the immune system has the ability to distinguish between self and non-self. Immune cells and other cells in the body usually coexist in a state known as self-tolerance. In abnormal situations (such as an autoimmune disease), the immune system can wrongly identify self as non-self and execute a misdirected immune attack.
According to Medscape, the altered development and function of B-cells may play a prominent role in many rheumatic disorders. The concept of B-cell depletion therapy is being researched as a treatment for diseases such as:
- rheumatoid arthritis
- lupus/systemic lupus erythematosus
- Sjogren's syndrome
- Behcet's disease
B-Cell Depletion for Rheumatic Diseases. Medscape.
NIH Pub 03-5423
During the 1960s, B-cells were first defined (and distinguished from thymus-derived T cells) in birds, which have a bursa. A decade later, after examining almost every other organ including the appendix, researchers finally discovered that mammalian B-cells develop in the bone marrow. The fact that 'bone marrow', like bursa, starts with a 'B' is a coincidence.