Over the last 20 years with improved awareness, earlier diagnosis and better techniques to diagnose, type and treat AL amyloidosis, many people are achieving a disease remission and living normal lives. However, AL amyloidosis remains a complicated disease that without treatment often has a very poor outcome, particularly if the heart is involved or the disease is diagnosed late. Early diagnosis is still the key to more effective treatment.
What causes AL amyloidosis?
Normal plasma cells, antibodies and free light chains
Before talking about what causes AL amyloidosis, first a few words about the normal situation in the human body.
Plasma cells are a special kind of white blood cell which are part of the body’s immune system. Plasma cells live in the bone marrow and their job is to make antibodies which are also known as immunoglobulins. Antibodies are a special type of protein and are part of the body’s defense system against infection. The human body is very adaptable and can make thousands of different antibodies in order to deal with many different infections. Once antibodies have done their job they are broken down and recycled in the body.
Each antibody molecule (or immunoglobulin) is made of two “heavy” chains and two “light” chains joined together (see diagram at right). The light chains can be of two types, Kappa or Lambda. When the immune system makes antibodies, light chains are made in excess of the amount needed to produce an antibody. These excess light chains circulate in the blood as free light chains.. Normally everyone has small amounts of kappa and lambda free light chains in their blood. These light chains circulate in the blood, cause no harm, and are excreted in the urine.
Plasma cells diseases and amyloid forming free light chains
In AL amyloidosis, plasma cells in the bone marrow begin to proliferate or grow abnormally, a situation known as a plasma cell disorder. Usually this buildup of plasma cells is benign but in some cases the growth of plasma cells can be malignant, that is, a cancer of the bone marrow called multiple myeloma. These abnormal plasma cells make large amounts of a single type of free light chain. The free light chain proteins fold in an abnormal way, become amyloid fibrils and progressively deposit in any of the tissues and organs of the body, except the brain. This deposition slowly interferes with organ and tissue function. Without treatment to slow or stop this amyloid being produced and deposited, organ failure occurs.