A Bence Jones protein is a substance found in the urine of people with multiple myeloma, a disease where blood cells in the bone marrow become malignant, or cancerous. Bence Jones proteins may also be found in the urine in association with certain other cancers of the blood. The protein was named after the English physician who discovered it, Henry Bence Jones.
One type of white blood cell, known as a B-lymphocyte, is part of the body's immune system, and is involved in the production of what are called immunoglobulins, otherwise known as antibodies. There are different lines of B-lymphocytes, each producing its own particular type of immunoglobulin which is involved in defending the body from foreign substances such as bacteria. If a B-lymphocyte line becomes malignant, typically the number of cells increases and large amounts of immunoglobulins are seen.
A single immunoglobulin, or monoclonal globulin protein, is generally made up of four protein chains, two heavy chains and two light chains. It is the light chain which, when separated from the rest of the immunoglobulin, constitutes the Bence Jones protein. In multiple myeloma, the malignant B-lymphocyte line produces a great number of its specific kind of immunoglobulin, which can be measured in the blood. At the same time, lots of the immunoglobulin light chains, each of which is a Bence Jones protein, can be detected in the urine and this is helpful in diagnosing the disease.
Multiple myeloma is the most common of the cancers associated with bone marrow, and is more frequently found in men and older people. Symptoms of bone loss and pain are experienced, and fractures may occur. As large amounts of Bence Jones protein have to be excreted by the kidneys, sometimes the kidneys can fail. Chemotherapy and radiotherapy may be used to treat the disease and the outlook depends on the severity of the disease, but even the worst cases may survive for up to about three years with treatment.
Bence Jones protein is also found in the urine in a disease known as Waldenström's macroglobulinemia. Here, as in multiple myeloma, there is a malignant change in one of the B-lymphocyte lines and excess amounts of lymphocytes are produced together with their corresponding immunoglobulins. There are different symptoms from multiple myeloma, in that kidney failure and bone loss are less common, while organs such as the liver and spleen may be enlarged. Treatment is usually only administered when patients develop symptoms, and commonly includes the use of chemotherapy and other drugs. The disease most often affects the elderly and on average people with this disease survive for around seven or eight years.